Name: discovering middle ear anatomy by transcanal endoscopic ear surgery: a dissection manual
Uploaded: 2018-01-11T13:00:00.000+00:00
Duration: 10 min 40 s
Description: Watch this Scientific Journal Video about Discovering Middle Ear Anatomy by Transcanal Endoscopic Ear Surgery: A Dissection Manual at JoVE.com

<p class="jove_content">La présente étude a été approuvée par le Conseil d’examen de l’établissement local (KEK-être 2016-00887).</p>
<p class="jove_title">1. préparation de l’échantillon</p>
<ol><li>Positionner un matelas sous vide sur la table de dissection et couvrir avec une couverture stérile. Posez le spécimen anatomique en position chirurgicale sur le matelas avec la tête légèrement tournée vers le côté controlatéral.</li>
	<li>Rétracter le tragus avec un crochet souple vers le côté controlatéral.</li>
	<li>Couvrir le spécimen avec une couverture en épargnant l’oreille externe, juste comme dans la salle d’opération.<br>Remarque : Consultez la <strong>Table des matières</strong> pour une liste complète du matériel requis.</li>
</ol><p class="jove_title">2. mise en route</p>
<ol><li>Adopter une position confortable ou une position assise et régler l’écran de l’endoscope. Il s’agit d’une question importante pour empêcher le durcissement des muscles du cou et donc plus rapide épuisement.</li>
	<li>Effectuer le blanc dans votre menu de l’appareil d’équilibrage et appliquez une goutte de la solution antibuée sur l’extrémité de l’endoscope.</li>
	<li>Tenir les instruments chirurgicaux dans votre main dominante et l’endoscope dans l’autre main.</li>
	<li>Introduire le 0°, diamètre 3 mm et endoscope longueur 15 cm dans l’EAC. Comme première tâche, nettoyer le CCE soigneusement de cérumen éventuellement présents en utilisant le tube d’aspiration. Rincez le CCE avec de l’eau. Couper les cheveux à l’intérieur de la CAE avec une paire de petits ciseaux pour empêcher l’encrassement lors de chaque passage de l’endoscope.</li>
	<li>Une fois que le CCE est propre, inspecter la membrane tympanique (TM). Identifier :<br>-Malleus avec processus abrégé, manubrium et umbo<br>-Anneau de la membrane tympanique<br>-Pars flaccida (membrane Shrappnel)</li>
</ol><p class="jove_title">3. élévation du rabat Tympano-méatique (TMF)</p>
<p class="jove_content">Remarque : Dans la chirurgie de l’oreille endoscopique, l’IGR s’effectue légèrement plus petits et dans une forme triangulaire. C’est le peu d’espace à l’intérieur de l’EAC.</p>
<ol><li>Inciser la peau EAC supérieurement, légèrement antérieur du processus abrégé du marteau à l’aide d’une faucille ou un couteau rond.</li>
	<li>Prolonger l’incision à la partie postérieure et supérieure du CCE et de prolonger l’incision pour la bordure antérieure et inférieure du TM pour configurer un rabat de forme triangulaire.</li>
	<li>Avec le couteau rond angle de 45°, exposer l’os et élevez la peau jusqu'à atteindre l’anneau. Il est important de se conformer strictement à l’OS.</li>
	<li>Élever l’anneau avec le couteau rond pour accéder à la cavité tympanique (TC). La muqueuse de la TC est un peu plus transparente que la peau et est incisée au niveau des chorda timbales à l’aide d’un crochet.</li>
	<li>Mobiliser l’annulus inférieurement et vers l’avant en utilisant le dissecteur de Thomassin.</li>
	<li>Identifier supérieurement le ligament latéral postérieur du marteau (PLML). Ce ligament représente la limite inférieure de l’espace Prussak. Saisir le ligament avec la pince de Hartmann et tirez doucement vers l’avant en direction de l’umbo jusqu’en découvrant le processus abrégé du marteau.</li>
	<li>Disséquer doucement l’espace Prussak antérieure jusqu'à l’insertion supérieure antérieure de l’annulus. Maintenant identifier :<br>-Anneau<br>-Chorda timbales<br>-Malléolaire posterior ligament<br>-Latérale malléolaire ligamenteuses pli<br>-Pli ligamenteuses malléolaire antérieure<br>-Espace Prussak</li>
</ol><p class="jove_title">4. détachement de l’IGR de la poignée de la Malleus</p>
<ol><li>Depuis le processus abrégé du malleus, continuer la dissection et Inciser le périoste du manche vers l’umbo malléolaire avec un dissecteur d’aiguille. Il est important de se détacher de la TM dans le bon plan pour éviter la perforation accidentelle.</li>
	<li>Détacher le TM complètement du manubrium. Une cottonoid sèche peut être utile, car elle facilite l’identification de la couche correcte et sa dissection.</li>
	<li>Après avoir atteint l’umbo, couper la couche fibreuse restante du TM à l’aide d’un micro-ciseaux.</li>
	<li>Placez maintenant le rabat entier sur la paroi antérieure du CCE pour permettre un accès gratuit à la TC. Identifier :<br>-Couche fibreuse de la membrane tympanique<br>-Anneau supérieur antérieure<br>-Umbo, manubrium et processus abrégé malleus<br>-Chorda timbales antérieur le marteau</li>
</ol><p class="jove_title">5. l’oreille moyenne Exploration</p>
<p class="jove_content">Remarque : Cette partie de la dissection favorise la reconnaissance et la répétition de l’anatomie de l’oreille moyenne. Chaque subdivision du TC devrait être étudiée séparément à l’aide d’endoscopes 0° et 45°. Présenter éventuellement les plis ou adhésions doivent soigneusement être retirées.</p>
<ol><li>Epitympanum. Identifier :<br>-Marteau : Cou, processus abrégé, manubrium et umbo<br>-Enclume : Corps, long processus, processus lenticulaire, commune d’incudostapedial<br>-Épitympanique diaphragme : ligaments malléolaire antérieur et latéral, pli ligamenteuses latéral incudomalleolar<br>-Colonne vertébrale antérieure et postérieure<br>-Chorda timbales<br>-Des modèles d’isthme et ventilation tympaniques à l’antre<br>-Cochleariform processus<br>-Le muscle tenseur timbales, tendon et canal osseux<br>-Pli tenseur</li>
	<li>Mesotympanum. Identifier :<br>-Étrier : Capitule, crus antérieures et postérieures, de la semelle<br>-Tendon du muscle stapédiens<br>-Eminence pyramidale<br>-OS promontoire<br>-Nerf de Jacobson avec artère tympanique inférieure</li>
	<li>Retrotympanum : Si les adhésions sont présentes ils doivent enlever soigneusement. Changer la position du chirurgien pour le côté controlatéral facilite l’accès à la retrotympanum par angulée optique (45°). Identifier :<br>-Récréation faciale<br>-Sinus postérieur<br>-Ponticulus<br>-Timbales sinus<br>-Subiculum<br>-Eminence styloïdes<br>-Sinus subtympanic<br>-OS Fustis<br>-Zone concamerata<br>-Niche de la fenêtre ronde avec tegmen, pilier antérieur et postérieur<br>-Membrane de la fenêtre ronde<br>-Canalicule Subcochlear<br>-Finiculus</li>
	<li>Hypotympanum<br>-Hypotympanic cellules<br>-Estimer la localisation de la JVB si non visible</li>
	<li>Protympanum. Identifier :<br>-Protiniculus<br>-Artère carotide interne<br>-Trompe d’Eustache (HE)</li>
	<li>Équipe de l’articulation incudostapedial et retirer l’enclume. Avec une curette supprimer l’écu de Sobieski. Identifier :<br>-Tympanique segment du nerf facial<br>-Latérale canal semicirculaire<br>-Antre<br>-COG ou crête transversale<br>-Timbales tegmen</li>
	<li>Couper le tendon du muscle tenseur du tympan et retirer le marteau. Identifier :<br>-Epitympanum antérieure<br>-Géniculé</li>
</ol>

<ol>
	<li>Presutti, L., Marchioni, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> <em style='font-style: italic'>Endoscopic Ear Surgery</em>. , (2015).</li><li>Weiss, M. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surgery+for+recurrent+and+residual+cholesteatoma.">Surgery for recurrent and residual cholesteatoma.</a> <em style='font-style: italic'>Laryngoscope</em>. <b>102</b>, 145-151 (1992).</li><li>Pickett, B. P., Cail, W. S., Lambert, P. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sinus+tympani:+anatomic+considerations,+computed+tomography,+and+a+discussion+of+the+retrofacial+approach+for+removal+of+disease.">Sinus tympani: anatomic considerations, computed tomography, and a discussion of the retrofacial approach for removal of disease.</a> <em style='font-style: italic'>Am J Otol</em>. <b>16</b>, 541-550 (1995).</li><li>James, A. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endoscope+or+microscope-guided+pediatric+tympanoplasty?+Comparison+of+grafting+technique+and+outcome.">Endoscope or microscope-guided pediatric tympanoplasty? Comparison of grafting technique and outcome.</a> <em style='font-style: italic'>Laryngoscope</em>. , (2017).</li><li>Tarabichi, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endoscopic+management+of+limited+attic+cholesteatoma.">Endoscopic management of limited attic cholesteatoma.</a> <em style='font-style: italic'>Laryngoscope</em>. <b>114</b> (7), 1157-1162 (2004).</li><li>Bonali, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+variants+of+the+retro-+and+hypotympanum:+an+endoscopic+anatomical+study.">The variants of the retro- and hypotympanum: an endoscopic anatomical study.</a> <em style='font-style: italic'>Eur Arch Otorhinolaryngol</em>. , (2017).</li><li>Bennett, M. L., Zhang, D., Labadie, R. F., Noble, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+Middle+Ear+Visualization+With+Endoscopy+and+Microscopy.">Comparison of Middle Ear Visualization With Endoscopy and Microscopy.</a> <em style='font-style: italic'>Otol Neurotol</em>. <b>37</b> (4), 362-366 (2016).</li><li>Anschuetz, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+Ovine+Model+for+Exclusive+Endoscopic+Ear+Surgery.">An Ovine Model for Exclusive Endoscopic Ear Surgery.</a> <em style='font-style: italic'>JAMA Otolaryngol Head Neck Surg</em>. <b>143</b> (3), 247-252 (2017).</li><li>Wang, M. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+costs+and+quality+of+operative+training+for+residents+in+tympanoplasty+type+I.">The costs and quality of operative training for residents in tympanoplasty type I.</a> <em style='font-style: italic'>Acta Otolaryngol</em>. <b>129</b>, 512-514 (2009).</li><li>Dedmon, M. M., Kozin, E. D., Lee, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+a+Temporal+Bone+Model+for+Transcanal+Endoscopic+Ear+Surgery.">Development of a Temporal Bone Model for Transcanal Endoscopic Ear Surgery.</a> <em style='font-style: italic'>Otolaryngol Head Neck Surg</em>. <b>153</b> (4), 613-615 (2015).</li><li>Barber, S. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=3D-printed+pediatric+endoscopic+ear+surgery+simulator+for+surgical+training.">3D-printed pediatric endoscopic ear surgery simulator for surgical training.</a> <em style='font-style: italic'>Int J Pediatr Otorhinolaryngol</em>. <b>90</b>, 113-118 (2016).</li></ol>

<p class="jove_content">Les auteurs ne déclarent aucun conflit d’intérêts. L’est titulaire d’une bourse de recherche de la Fondation Bangerter-Rhyner, Berne et par Karl Storz GmbH, Tuttlingen, Allemagne. Les bailleurs de fonds n’avaient aucun rôle dans la conception de l’étude, la collecte de données et analyse, décision de publier ou préparation du manuscrit.</p>

<p class="jove_content">Le manuel de dissection proposée est utile pour effectuer une dissection complète anatomique de l’oreille moyenne. Présentant une connaissance approfondie de l’anatomie de l’oreille moyenne est une condition préalable fondamentale pour toute intervention chirurgicale de l’oreille moyenne. Dissection de cadavres permet la manipulation de la caméra et les instruments chirurgicaux dans la CAE de formation. Pour un novice à EES, la coordination entre le œil et de l’instrument, mais aussi la manipulation correcte de l’endoscope (pas de flexion, manoeuvrant entre les structures anatomiques importantes comme les osselets dans un espace limité et de l’image en deux dimensions) sont critiques étapes pour démarrer avec ce nouveaux technique chirurgicale.</p>
<p class="jove_content">La principale limitation de ce modèle par rapport à la situation réelle chirurgicale est l’absence de saignement. Ceci est valable pour n’importe quel modèle de dissection de cadavres. Récemment, Edmond <em>et al</em>. décrit un modèle de l’OS temporal, où le saignement a été simulé pendant l’élévation de l’IGR. Ce modèle pourrait en fait être une bonne option pour les chirurgiens avancées déjà utilisée pour les EES. Dans notre expérience, la familiarisation initiale avec EES devrait être aussi facile que possible, étant donné que la manipulation des instruments est déjà une tâche difficile. La dissection de cadavres est considéré comme l’étalon-or pour l’enseignement chirurgical. Toutefois, il est soumis à des coûts élevés et des règles éthiques. En comparaison, les modèles synthétiques ou animaux peuvent l’emporter sur ces questions<sup class="xref">8</sup><sup>,</sup><sup class="xref">11</sup>. Toutefois, la sensation tactile pour les tissus synthétiques modèles est difficile et la résolution de l’impression 3D n’est pas encore en mesure de fournir tous les détails qu'un spécimen anatomique peut. En revanche, le modèle animal fournit des propriétés des tissus excellent mais a une anatomie différente. On peut considérer le modèle cadavérique le seul modèle approprié pour l’enseignement anatomique, tandis que les modèles synthétiques et animaux constituerait un bon marché pour la formation en chirurgie.</p>
<p class="jove_content">Par rapport à la technique microscopique pour la dissection de l’oreille moyenne, l’endoscope permet l’observation et la préparation des structures délicates oreille moyenne par un orifice naturel, le CCE. Par conséquent, aucun os ne doit être retirée aux fins de l’accès et l’oreille moyenne peut être étudié dans son état naturel. En outre, l’endoscope permet une observation très proche de la structure anatomique et donc aussi de grossissement sans perdre l’illumination. Bien sûr, l’approche endoscopique n’enseigne pas la mastoïdectomie, pouvant être réalisées sur le même échantillon après dissection endoscopique. La technique endoscopique pour la chirurgie de l’oreille se répand au niveau international et par conséquent la nécessité d’une formation chirurgicale appropriée augmentera.</p>

<p class="jove_content">L’oreille moyenne est situé dans le centre de l’OS temporal et porte une anatomie très complexe. Les structures plus contigus sont le nerf facial (FN), la cochlée (CO), la chaîne ossiculary (OC), l’ampoule de la veine jugulaire (JVB) et l’artère carotide interne (ICA). La fente de l’oreille moyenne est anatomiquement divisée en cinq parties : l’epitympanum se trouve supérieurement et est interconnecté par l’antre pour le système de cellules d’air mastoïdien (Mac) ; le retrotympanum postérieur est un système de ponts osseux et sinus plus ou moins superficielles ; bas se trouve le hypotympanum ; en avant est le protympanum avec sa connexion à la trompe d’Eustache ; et dans le centre, se trouve la mesotympanum<sup class="xref">1</sup>.</p>
<p class="jove_content">L’accès physiologiques à travers le conduit auditif externe (CAE) est étroit. Par conséquent, l’approche chirurgicale standard pour l’oreille moyenne nécessite une incision de rétroauriculaires et le forage des Mac. Ces types d’interventions sont effectuées à l’aide d’un microscope opératoire. Son introduction a été une étape importante dans la chirurgie otologique, puisqu’elle a permis le traitement des structures microscopiques oreille moyenne. Toutefois, le microscope bénéficie d’une vue droite forcée et certaines régions, en particulier les timbales de sinus, sont difficiles d’accès. Il assume le risque de maladie résiduelle surtout pendant le Cholestéatome chirurgie<sup class="xref">2</sup><sup>,</sup><sup class="xref">3</sup>. En outre, les tissus sains de l’EAC, MACS et oreille moyenne doivent être retirés simplement aux fins de l’accès. Cela s’étend non seulement de la durée d’utilisation, mais aussi représente plus de morbidité chirurgicale et une guérison prolongée du temps<sup class="xref">4</sup>.</p>
<p class="jove_content">Des progrès récents menés à l’introduction de l’endoscope est un instrument puissant pour la chirurgie de l’oreille. L’endoscope a été utilisée pour aider le chirurgien conventionnellement pour visualiser les zones cachées de l’oreille moyenne. Raffinements techniques et chirurgicaux a permis l’introduction de l’endoscope, le principal mode d’outil<sup class="xref">5</sup>. Les principaux avantages de l’endoscope sont les points de vue panoramiques et grand angle de l’oreille moyenne. Par exemple, l’autre caché rétro - et hypotympanum peuvent être consultés en utilisant une approche exclusive transcanal endoscopique sans un canaloplasty<sup class="xref">6</sup>. Une étude récente a montré une visibilité supérieure de tous les compartiments d’oreille moyenne à l’aide de l’endoscope par rapport à la technique microscopique<sup class="xref">7</sup>. L’utilisation des endoscopes inclinés (30° à 45°) plus accroît la visibilité et permet une dissection et une vue des zones plus cachés de l’oreille moyenne.</p>
<p class="jove_content">Cependant, chirurgie de l’oreille endoscopique (See) est une technique chirurgicale avec une seule main, comme l’aiguille des secondes est généralement titulaire l’endoscope. Cette question et l’espace étroit à l’intérieur de l’EAC nécessitent une formation pour améliorer les compétences du chirurgien pour appliquer en toute sécurité la technique chez les patients. En général, l’étalon-or pour la formation en chirurgie est réputé être dissection cadavérique. En cas d’indisponibilité des spécimens provenant de cadavres ou des enjeux éthiques locaux, un modèle animal pour la formation de chirurgie de l’oreille endoscopique a été récemment décrit<sup class="xref">8</sup>. Formation en chirurgie est considérée comme un facteur important dans la formation des stagiaires à une nouvelle technique<sup class="xref">9</sup>.</p>
<p class="jove_content">Malgré l’importance de la formation en chirurgie, une description concise des considérations importantes sur la façon d’effectuer une dissection cadavérique fait encore défaut dans la littérature. Le but de cet article est de décrire la méthodologie de dissection endoscopique oreille cadavériques, exclusivement. De plus, nous visons à fournir un guide complet sur l’anatomie endoscopique oreille moyenne.</p>

<table><tbody><tr><td>Endoscopes: 3mm diameter, 15cm length, 0&amp;deg; and 45&amp;deg;</td><td>Karl Storz</td><td></td><td></td></tr><tr><td>Otologic dissectors, round knifes, hooks, curette, microscissors (Bellucci) and microforceps (Hartmann)</td><td>Karl Storz</td><td></td><td></td></tr><tr><td>Straight and curved suction tubes</td><td>Karl Storz</td><td></td><td></td></tr><tr><td>Flexible hook</td><td></td><td></td><td></td></tr><tr><td>Scissors</td><td></td><td></td><td></td></tr><tr><td>Video Equipment&lt;br/&gt; - HD-scree&lt;br/&gt; - 3-CCD camera&lt;br/&gt; - Xenon light source</td><td>Karl Storz</td><td></td><td></td></tr><tr><td>Cadaveric Head</td><td>-</td><td></td><td></td></tr><tr><td>Vacuum matress</td><td></td><td></td><td></td></tr><tr><td>Aspirator</td><td></td><td></td><td></td></tr><tr><td>Consumables&lt;br/&gt; - Water to rinse&lt;br/&gt; - Antifog solution&lt;br/&gt; - Cotton pads&lt;br/&gt; - Cottonoid pledges&lt;br/&gt; - Gown&lt;br/&gt; - Gloves&lt;br/&gt; - Mask</td><td></td><td></td><td></td></tr></tbody></table>

discovering middle ear anatomy by transcanal endoscopic ear surgery: a dissection manual

<p class="jove_content">L’oreille moyenne est situé dans le centre de l’OS temporal et porte une anatomie très complexe. L’approche exclusivement endoscopique transcanal récemment introduites à l’oreille moyenne est une technique peu invasive, épargnant l’os et la muqueuse de l’OS mastoïde, étant donné que l’oreille moyenne est accessible via le conduit auditif externe. Cette nouvelle méthode a plusieurs avantages par rapport aux approches traditionnelles (microscopiques) de l’oreille moyenne, telles que la vue panoramique grand angle de l’anatomie, la possibilité d’approcher et d’agrandir les petites structures et la possibilité de regarder autour de la coin à l’aide d’endoscopes inclinées.</p>
<p class="jove_content">La méthode de dissection cadavériques présentée ici se compose d’un aperçu sur les exigences techniques et une description précise d’un protocole étape par étape pour découvrir l’anatomie de l’oreille moyenne. Chaque étape et chaque structure anatomique sont décrite avec soin afin d’offrir un guide complet sur l’anatomie de l’oreille endoscopique. À notre avis, cela est particulièrement important de n’importe quel novice en chirurgie endoscopique oreille où il fournit les connaissances anatomiques approfondies et peut améliorer des compétences chirurgicales.</p>

<p class="jove_content" fo:keep-together.within-page="1">Nous avons disséqué un total de cinq spécimens de toute tête et 12 OS temporal (n = 22 côtés) en suivant les instructions décrites. Les différentes régions du TC ont été documentées photographiquement et analyse plus poussée. Toutes les régions ont été explorées à l’aide d’endoscopes 0° et 45°. Nous avons effectué une exploration complète de toutes les régions anatomiques et identifié les repères anatomiques tout mentionnés.</p>
<p class="jove_content" fo:keep-together.within-page="1">Les structures anatomiques sont illustrées selon la progression de la dissection. <strong class="xfig">La figure 1</strong> illustre l’espace Prussak et les ligaments malléolaire, tandis que la <strong class="xfig">Figure 2</strong> montre l’anatomie après élévation complète de TMF. La vue grand angle permet la visualisation de la méso - et hypotympanum ainsi que certaines parties de l’épi-, rétro- et protympanum. Dans la <strong class="xfig">Figure 3</strong>, la retrotympanum supérieure est montré tel qu’il apparaît dans un endoscope de 45 °, alors que le chirurgien se tient sur le côté opposé de la table. <strong class="xfig">La figure 4</strong> illustre en détail le protympanum avec un ICA déhiscent. Après le retrait de l’OC et transcanal atticotomy l’epitympanum est inspecté jusqu'à ce que le canal semicirculaire latéral et l’antre comme illustré à la <strong class="xfig">Figure 5</strong>.</p>
<p class="jove_content" fo:keep-together.within-page="1">Aucun spécimen ne requis canaloplasty pour effectuer une exploration complète de la cavité tympanique. L’identification des structures anatomiques n’a pas été possible dans tous les échantillons à l’aide de la portée de 0° et 45°. Cependant, l’exploration complète de la retrotympanum, en particulier la cavité faciale et les timbales de sinus, n’était pas possible dans 27 % des cas (n = 6), étant donné que ces baies osseuses étaient trop profonds pour être complètement exploré.</p>
<p class="jove_content" fo:keep-together.within-page="1"><img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/56390/56390fig1.jpg"><br><strong class="xfig">La figure 1</strong>. Oreille gauche, endoscope 0° : vue de l’espace Prussak et les plis ligamenteuses environnantes du marteau. TM : membrane tympanique, un : anneau, u: umbo, sp : court processus de malleus, amf : pli malléolaire antérieur, lmf : malléolaire latérale rabattable, plm : ligament croisé postérieur du malleus, ct : timbales de chorda, * : Prussak espace <a href="//cloudflare.jove.com/files/ftp_upload/56390/56390fig1large.jpg" target="_blank">s’il vous plaît cliquez ici pour visionner une version agrandie de cette Figure.</a></p>
<p class="jove_content" fo:keep-together.within-page="1"><img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/56390/56390fig2.jpg"><br><strong class="xfig">La figure 2</strong>. Oreille gauche, endoscope 0° : vue de la cavité tympanique après élévation du rabat tympano-méatique. Le méso - et hypotympanum ainsi que certaines parties de l’épi-, rétro - et protympanum sont visualisées. PR : promontoire, jn : nerf de Jacobson, hy : hypotympanum, fi : finiculus, sst : sinus subtympanicus, se : eminence styloïdes, pe : éminence pyramidale, st : tendon stapédiens, isj : incudostapedial mixte, fn : nerf facial, u: umbo, m: manubrium, sp : processus abrégé, n: cou de le malleus, ttm : le muscle tenseur tympanique, ttf : tenseur tympanique pli, ica. Artère carotide interne <a href="//cloudflare.jove.com/files/ftp_upload/56390/56390fig2large.jpg" target="_blank">s’il vous plaît cliquez ici pour visionner une version agrandie de cette figure.</a></p>
<p class="jove_content" fo:keep-together.within-page="1"><img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/56390/56390fig3.jpg"><br><strong class="xfig">La figure 3</strong>. Droite oreille, endoscope de 45°, position controlatérale du chirurgien : la retrotympanum supérieure est illustrée à l’aide d’un endoscope incliné. FN : nerf facial, s: étrier, st : tendon stapédiens, ps : sinus postérieur, fp : semelle, po : ponticulus, pe : éminence pyramidale, s’asseoir : timbales de sinus, sub, subiculum se : eminence styloïdes, sst : sinus subtympanicus, ap : pilier antérieur, teg : tegmen, pp : postérieur pilier, rw : fenêtre ronde, fu : fustis, tu : subcochlear tunnel <a href="//cloudflare.jove.com/files/ftp_upload/56390/56390fig3large.jpg" target="_blank">s’il vous plaît cliquez ici pour visionner une version agrandie de cette figure.</a></p>
<p class="jove_content" fo:keep-together.within-page="1"><img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/56390/56390fig4.jpg"><br><strong class="xfig">La figure 4</strong>. Oreille gauche, endoscope de 45° : vue de la protympanum détaillée. Notez la carotide déhiscente. et : trompe d’Eustache, ica : l’artère carotide interne, pro : protiniculus, co : cochlée, ttm : muscle timbales tenseur <a href="//cloudflare.jove.com/files/ftp_upload/56390/56390fig4large.jpg" target="_blank">s’il vous plaît cliquez ici pour visionner une version agrandie de cette figure.</a></p>
<p class="jove_content" fo:keep-together.within-page="1"><img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/56390/56390fig5.jpg"><br><strong class="xfig">Figure 5</strong>. Oreille gauche, endoscope 0° : après le retrait de l’enclume et la malléole et curetage de l’écu de Sobieski, un large aperçu de la timbale tegmen et l’antre est illustré ici. Notez le canal semicirculaire latéral et muscle tenseur tympanique étant sur une seule ligne au croisement du nerf facial. TEG : tegmen, cog : COG ou crête transversale, gg : géniculé, cp : cochleariform processus, ttm : tenseur tympanique muscle, lsc : canal semicirculaire latéral, fn : segment tympanique du nerf facial, s: étrier, co : cochlée, ica : l’artère carotide interne <a href="//cloudflare.jove.com/files/ftp_upload/56390/56390fig5large.jpg" style="font-size: 14px;" target="_blank">s’il vous plaît Cliquez ici pour visionner une version agrandie de cette figure.</a></p>

Watch this Scientific Journal Video about Discovering Middle Ear Anatomy by Transcanal Endoscopic Ear Surgery: A Dissection Manual at JoVE.com

Discovering Middle Ear Anatomy by Transcanal Endoscopic Ear Surgery: A Dissection Manual

<p class="jove_content">Le but de cet article est de décrire la méthodologie de dissection endoscopique oreille cadavériques, exclusivement. De plus, nous visons à fournir un guide complet sur l’anatomie endoscopique oreille moyenne.</p>

Découvrir l’anatomie oreille moyenne par chirurgie endoscopique oreille Transcanal : un manuel de Dissection

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64.3K vues.  University of Bern. Le but de cet article est de décrire la méthodologie de dissection endoscopique oreille cadavériques, exclusivement. De plus, nous visons à fournir un guide complet sur l’anatomie endoscopique oreille moyenne.

Vidéo: Discovering Middle Ear Anatomy by Transcanal Endoscopic Ear Surgery: A Dissection Manual

Cell Structure

<h4>Background</h4>
<p>Cells represent the most basic biological units of all organisms, whether it be simple, single-celled organisms like bacteria, or large, multicellular organisms like elephants and giant redwood trees. In the mid 19<sup>th</sup> century, the Cell Theory was proposed to define a cell, which states:</p>
<ul>
	<li>Every living organism is made up of one or more cells.</li>
	<li>The cells are the functional units of all organisms.</li>
	<li>All cells arise from preexisting cells.</li>
</ul>
<p>All cells share common features such as having a plasma membrane, a cytoplasm, DNA, and ribosomes. A plasma membrane is a phospholipid bilayer that surrounds the cell. This thin and fluid layer around the cells serves to isolate the cell&#8217;s contents from its environment and regulates the material exchange with its environment, while also facilitating interactions with other cells. Inside the plasma membrane, the cell is filled with a gel-like fluid called cytoplasm that contains organic molecules, salts, and other materials that are vital for the cell&#8217;s functions. Therefore, biochemical reactions that support life, which are known as metabolic processes, take place inside the cytoplasm. The types of metabolic processes that a cell can execute depend on its genetic information. All cells use DNA as the genetic material, which is the hereditary blueprint to construct cellular structures and products. Finally, all cells use ribosomes to synthesize their protein products.</p>
<p>There are two types of cells based on their genetic material location: prokaryotic, which means &#8220;before nucleus&#8221;, and eukaryotic, which means &#8220;true nucleus&#8221;. Therefore, while both types of organisms have DNA, prokaryotes like bacteria have nucleoids, or &#8220;nucleus-like&#8221; components instead of a nucleus, whereas eukaryotes possess true, membrane-bound nuclei to contain their DNA. Moreover, prokaryotes are relatively small, around 0.1&#8211;5.0 micrometers (&#181;m), in comparison to eukaryotes that can typically range from 10-100 &#181;m in size. The small size of prokaryotes allows quick and effortless distribution of materials within the cell and execution of metabolic processes, as well as swift removal of waste or other products from the cell. Hence, eukaryotic cells possess specialized structures known as organelles, such as mitochondria or Golgi apparatus, to enable the execution of vital functions.</p>
<h4>The Eukaryotic Cell</h4>
<p>The eukaryotic cell is a shared derived trait of all eukaryotes, meaning that it had a single origin that has since been inherited by all eukaryotes. The earliest eukaryotic cells are seen in fossils about 2.4 billion years ago, and are recognizable because they are larger than prokaryotic cells<sup>1</sup>. The origin of this cell type resulted from an endosymbiotic event in which one amoeba-like cell engulfed a micrococcal bacteria and formed a stable coexistence<sup>2</sup>. The engulfed bacteria evolved into the first energy-producing organelles, mitochondria, which are the aerobic metabolism organelles in the cell. Mitochondria have their own separate genome and are similar in size to prokaryotes. They contain two layers of membranes that enclose two distinct compartments. Some of the reactions that break down high-energy biomolecules occur in the inner compartment, whereas the outer compartment houses the reactions that capture the energy released from these compounds into adenosine triphosphate (ATP) molecules to be used as the energy currency of the cell.</p>
<p>Nuclei and mitochondria are not the only shared structures of eukaryotic cells. Other ubiquitous eukaryotic organelles are the smooth and rough endoplasmic reticulum (ER), Golgi apparatus, lysosomes and vacuoles. Endoplasmic reticulum simply means &#8220;network inside the plasma&#8221; and as its name indicates it is a large network of membranes inside the cell, especially around the nucleus. Parts of the rough ER extend from the nuclear membrane and are distinguished from the smooth ER by their rough appearance due to numerous ribosomes on their surface. Rough ER is the site for protein synthesis, such as the proteins that are embedded in the plasma membrane or the proteins that are secreted from the cell. In contrast, smooth ER produces lipid-based products but also contains enzymes to detoxify harmful chemicals. Hence liver cells contain abundant smooth ER. Also, muscle cells contain significant amounts of smooth ER because of the calcium-storing function of this organelle, which is essential for muscle contraction. The Golgi apparatus sorts, modifies, and packages cellular products inside vesicles, which fuse with the plasma membrane to release the products. Some of the proteins that are produced in the rough ER are intracellular digestive enzymes. These enzymes are packed in the Golgi apparatus into special vesicles called lysosomes. The major function of the lysosomes is to digest the food particles engulfed by the cell as well as old cell parts. Vacuoles are sacs of cell membrane that serve as storage units within cells. They may serve to store water to regulate the cell&#8217;s water content as well as store metabolic products or even poisonous molecules, depending on the cell type and the organism.</p>
<h4>Kingdom-specific Organelles</h4>
<p>Eukaryotic cells also developed distinct organelles, specific for each kingdom. For instance, kingdom Plantae and Animalia are both eukaryotic, however the organelles of plant and animal cells differ in key ways that allow them to carry out their lives as producers and consumers, respectively. Terrestrial plants need to grow tall and have rigid stems to hold leaves, which they use for photosynthesis. They also need to be able to retain water taken up by roots. Their cells reflect these specific needs. Unlike animal cells, plant cells have chloroplasts, which are used for photosynthesis and often contain the green pigment chlorophyll. Additionally, they are surrounded by cell walls, which are rigid outer layers made of cellulose to support growth and water retention. Because they need to store large amounts of water to maintain the water pressure in the cell, they have larger vacuoles than animal cells. In addition, plant cells also have another type of specialized storage organelles called plastids, which contain pigments as well as photosynthetic products such as starch. These differences are noticeable and distinguish plant cells from animal cells: plant cells generally have a regular, rectangular shape due to their rigid cell walls, while animal cells are rounded and more irregular.</p>
<h4>Microscopy</h4>
<p>Some cells, such as frog oocytes, are large enough to be seen with the naked eye, yet most cells cannot be seen without any visual aid. Therefore, scientists use microscopy techniques to study cell structures and distinguish cell types from one another. While microscopes are able to magnify objects that are difficult or impossible to be see with the human eye, most tissues naturally lack pigmentation. Therefore, solutions have been created that can selectively stain cells based on their molecular composition. This allows researchers to distinguish between organelles in a cell, tissue types in a plant stem, and fat layers in animals, just to name a few examples. Methylene blue dye stains nucleic acids of dead cells, binding to negatively charged DNA. Safranin solution is another biological dye that stains cell nuclei red. Cells only need to be in the staining solutions for a short period of time, and can be mounted immediately following the staining step. The commonly used mounting techniques are wet mount and oil immersion. A wet mount is created by collecting a sample and putting it on a glass slide with liquid between the slide and the coverslip. Cell samples are suspended in liquids like water or glycerol. Glycerol is better to use with live cultures, because it prevents the proliferation of bacteria<sup>3</sup>. Immersion oil can be added on top of the coverslip to improve viewing of the sample at high magnification. This is accomplished because the oil has the same refractive index as glass, which means that it allows light to pass through it as well as glass would. The glass-air interface scatters light more than oil or glass, so the clarity of the image is affected when samples are mounted &#8220;dry&#8221;, or without oil. Once the cells are stained and mounted, they are ready to be studied under the microscope.</p>
<p>There are various microscopy techniques from electron scanning technology that has allowed researchers to view objects on an atomic level to fluorescent live cell imaging that allows real-time monitoring of the movement of molecules within individual cells<sup>4</sup>. Bright-field microscopy is the simplest microscopy technique, requiring only a halogen source light, a condenser lens to focus the light, an ocular lens to view the image, and an objective lens to magnify the image. With any microscopy technique, it is important to understand the parts of a microscope before using one. In general, compound microscopes used for bright-field imaging have an eyepiece at the top of the scope, which is attached to the head and objectives. The eyepiece has a magnification of 10X, and objective lenses are set to a particular magnification in a range of 4X-100X. There are between three and five objectives on a standard microscope. The objectives point down to the stage, which is where a specimen is placed for viewing. The stage often has mechanical parts and stage clips to hold a slide and move it around while viewing. An aperture is a hole in the stage for light to pass through. This light is controlled by an adjustable condenser lens above an illuminator, or light source. To control the zoom of the stage for the object being viewed, microscopes feature coarse and fine focus adjustment knobs. The coarse focus knob moves on a larger scale than the fine focus, but they are on the same axis. The fine focus is useful when the object on the stage has been brought close to the objectives. It is important not to let the objective lens touch the object on the stage, as it can scratch the lens. Objects should always be first viewed on the lowest magnification objective and clearly focused before switching to higher magnification objectives.</p>
<p>Microscopy is an important tool for many aspects of the medical field including research, diagnosis, and treatment. This has the application of using nanotechnology in medicine, as a new treatment method in place of a more invasive surgery<sup>5</sup>. Surgeons also make use of microscopes, some of which have been modified to be mounted on a surgeon&#8217;s head and are operated with foot pedals. These are of much lower magnification than even the light microscopes used today, but they facilitate the safe execution of delicate procedures, such as optical and neurosurgery.</p>
<h4>References</h4>
<ol class="references">
	<li><strong>Bengtson S, Rasmussen B, Ivarsson M, Muhling J, Broman C, Marone F, Stampanoni M, Bekker A.</strong> Fungus-like mycelial fossils in 2.4-billion-year-old vesicular basalt. <em>Nature Ecology &#38; Evolution. </em>2017, Vol. 1, Article number: 0141.</li>
	<li><strong>Vellai T, Vida G.</strong> The origin of eukaryotes: the difference between prokaryotic and eukaryotic cells. <em>Proc. R. Soc. Lond. B. </em>1999, Vol. 266, 1571-1577.</li>
	<li><strong>Gouet V, Roger G, Fonty C, Andre P.</strong> Effects of glycerol on the growth, adhesion, and cellulolytic activity of rumen cellulolytic bacteria and anaerobic fungi. <em>Current Microbiology. </em>24, 1992, Vol. 4, 197-201.</li>
	<li><strong>Cognet L, Leduc C, Lounis B.</strong> Advances in live-cell single-particle tracking and dynamic super-resolution imaging. <em>Curr Opin Chem Biol. </em>2014, Jun; 20:78-85.</li>
	<li><strong>Asiyanbola B, Soboyejo W.</strong> For the surgeon: an introduction to nanotechnology. <em>J Surg Educ. </em>2008, Vol. 65, 2 (155-61).</li>
</ol>

Cell Structure: Visualizing Onion and Human Cells - Concept

Structure cellulaire

Background
Cells represent the most basic biological units of all organisms, whether it be simple, single-celled organisms like bacteria, or large, ...

Enseignement

JoVE Lab Manual

Biologie

Les bases

Scientific Measurement and Lab Skills

Two-Dimensional Graphs, Curve Fitting, and Standard Deviation - Procedure

Mesure scientifique et compétences de laboratoire

Source: Smaa Koraym at Johns Hopkins University, MD, USA

	Measuring Diameter and CircumferenceExpand
	Error can be introduced in any experiment, even ...

Chimie

Lab Manual Sub Articles

Extraction

Extraction: Liquid-Liquid and Acid-Base Extraction - Procedure

Source: Lara Al Hariri and Ahmed Basabrain at the University of Massachusetts Amherst, MA, USA

	Cellulose RecoveryExpand
	Extraction and filtration can ...

Lab Techniques

<p>Source: Smaa Koraym at Johns Hopkins University, MD, USA</p>
<ol class="note-items">
	<li data-note-item="1" data-parent-collapse=""><strong>Determining the Density of an Egg</strong><button class="expand">Expand</button>
	<p>Density is a measure of how compact a substance or object is, and it is calculated as mass divided by volume. When a dense object is placed in a liquid with a lower density, the object sinks; when the object is less dense than the liquid, it floats. When the densities are the same, the object will be suspended in the liquid. In this experiment, we&#39;ll determine the density of an egg by creating a solution with the same density. We&#39;ll measure the density of the salt solution using different volume measurement glassware and determine which is the most accurate.</p>
	<ul class="lab-items">
		<li data-sub-note-item="1-1">
		<div class="lab-step">To begin, wear the appropriate personal protective equipment, including close-toed shoes, long pants, long-sleeved shirt, lab coat, chemical splash goggles, and gloves.</div>
		</li>
		<li data-sub-note-item="1-2">
		<div class="lab-step">Measure the mass of the egg. Set a weigh boat on the balance and tare it. Carefully set the egg in the weigh boat while you record the mass in your notebook.</div>
		</li>
		<li data-sub-note-item="1-3">
		<div class="lab-step">Prepare the salt solution that will be used to suspend your egg. Use the 600-mL beaker and fill it 3/4 of the way full with deionized water.</div>
		</li>
		<li data-sub-note-item="1-4">
		<div class="lab-step">Gently place your egg in the beaker, and then add about one teaspoon of NaCl into the water. Stir the solution gently until the NaCl dissolves. Continue to add NaCl until the egg floats just below the surface.</div>
		</li>
		<li data-sub-note-item="1-5">
		<div class="lab-step">Use different glassware to measure the volume of the salt solution. Weigh the 50-mL graduated cylinder on the top loading balance and record the mass. Then, measure 20 mL of your salt solution and record the volume in your notebook. <strong>Note: </strong>Place a blank sheet of paper behind the graduated cylinder to read the volume more clearly. Always view the measurement at eye level and measure the volume from the bottom of the meniscus. The lines on the graduated cylinder are 0.2 mL apart, meaning that you can read the volume to the hundredths place.
		<h4><b>Table 1: Measuring Mass</b></h4>
		<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
			<tbody>
				<tr>
					<td style="text-align: center;"><strong>Container</strong></td>
					<td style="text-align: center;"><strong>Mass of empty container (g)</strong></td>
					<td style="text-align: center;"><strong>Mass of full containter (g)</strong></td>
					<td style="text-align: center;"><strong>Mass of solution (g)</strong></td>
					<td style="text-align: center;"><strong>Percent error</strong></td>
				</tr>
				<tr>
					<td>50-mL graduated cylinder</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
				<tr>
					<td>10-mL volumetric pipette</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
				<tr>
					<td>50-mL beaker</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
				<tr>
					<td>20-mL volumetric flask</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
			</tbody>
		</table>
		<a href="https://www.jove.com/CDNSource/lm/labs/41/Table_1._Measuring_Mass.xlsx" target="_blank">Click Here to download Table 1</a></div>
		</li>
		<li data-sub-note-item="1-6">
		<div class="lab-step">Weigh the filled graduated cylinder and record the mass in your notebook. Then, pour the salt solution back into the 600-mL beaker.</div>
		</li>
		<li data-sub-note-item="1-7">
		<div class="lab-step">Use the volumetric pipette to measure volume. First, weigh the empty 50-mL beaker and record the mass in your notebook. Then, carefully measure 10 mL of the salt solution using the volumetric pipette and dispense the salt solution into the beaker.</div>
		</li>
		<li data-sub-note-item="1-8">
		<div class="lab-step">Measure another 10 mL and add it to the beaker. Weigh the filled beaker and record the mass in your notebook. Then, empty, rinse, and dry the beaker.</div>
		</li>
		<li data-sub-note-item="1-9">
		<div class="lab-step">Use the volumetric flask to measure volume. Weigh the empty 20-mL volumetric flask and record the mass. Then, carefully fill the flask with the salt solution to just below the 20-mL fill mark. Do not fill it all the way. Use an eyedropper to finish filling the flask so that the bottom of the meniscus just touches the fill line on the neck of the flask. Then, weigh the full flask and record the weight.</div>
		</li>
		<li data-sub-note-item="1-10">
		<div class="lab-step">Lastly, use the 50-mL beaker to measure volume. Weigh the empty beaker, then fill the beaker with salt solution to the 20-mL line and weigh the full beaker. Record the masses in your notebook.</div>
		</li>
		<li data-sub-note-item="1-11">
		<div class="lab-step">Measure the displacement of the egg when it is submerged in the salt solution. First, remove the egg and look at the level of the salt solution in the 600-mL beaker. <strong>Note:</strong> If it is not at a marked line, add deionized water to the solution so that the meniscus is at a readable volume and record the volume.&#160;
		<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
			<tbody>
				<tr>
					<td><strong>Measurements</strong></td>
					<td><strong>Salt solution using 20-mL volumetric flask&#160;</strong></td>
					<td><strong>Egg</strong></td>
				</tr>
				<tr>
					<td>Mass (g)</td>
					<td></td>
					<td></td>
				</tr>
				<tr>
					<td>Displacement of water (cm)</td>
					<td style="text-align: center;">-</td>
					<td></td>
				</tr>
				<tr>
					<td>Inner diameter of 600-mL beaker (cm)</td>
					<td style="text-align: center;">-</td>
					<td></td>
				</tr>
				<tr>
					<td>Volume (cm&#179;)</td>
					<td style="text-align: center;">-</td>
					<td></td>
				</tr>
				<tr>
					<td>Volume (mL)</td>
					<td style="text-align: center;">20</td>
					<td></td>
				</tr>
				<tr>
					<td>Density (g/mL)</td>
					<td></td>
					<td></td>
				</tr>
			</tbody>
		</table>
		<strong><a href="https://www.jove.com/CDNSource/lm/labs/41/Table_2._Measuring_Density.xlsx" target="_blank">Click Here to download Table 2</a> </strong></div>
		</li>
		<li data-sub-note-item="1-12">
		<div class="lab-step">Gently place the egg in the beaker.</div>
		</li>
		<li data-sub-note-item="1-13">
		<div class="lab-step">Use a ruler to measure the new height of the solution level and record the height. Then, place the ruler across the top of the beaker to measure the inner diameter.</div>
		</li>
		<li data-sub-note-item="1-14">
		<div class="lab-step">Calculate the new volume from these measurements. Subtract the initial volume to obtain the displacement of the egg (volume).</div>
		</li>
		<li data-sub-note-item="1-15">
		<div class="lab-step">To clean up from the experiment, return the egg to your instructor and pour the salt solution down the sink. Rinse all used glassware with tap water and set them out to dry. Finally, return the sodium chloride to your instructor.</div>
		</li>
	</ul>
	</li>
	<li data-note-item="2" data-parent-collapse=""><strong>Results</strong><button class="expand">Expand</button>
	<ul class="lab-items">
		<li data-sub-note-item="2-1">
		<div class="lab-step">Calculate the mass of the solution in each of the different volumetric glassware by subtracting the empty glassware mass from the full glassware mass.</div>
		</li>
		<li data-sub-note-item="2-2">
		<div class="lab-step">Keep track of uncertainty in your measurement by using significant figures. For example, when we look at the graduated cylinder measurement, the weight of the empty container is 90.92, and the weight of the full container is 111.59. The weight measurements have significant figures to the hundredths place, so it is important that significant figures are maintained throughout our calculations. Thus, the mass of the 20-mL salt solution is 20.67 g.</div>
		</li>
		<li data-sub-note-item="2-3">
		<div class="lab-step">The 50-mL beaker weighed 28.65 g when it was empty and 47.96 g when it contained 20 mL of salt solution. Therefore, the mass of 20 mL of the salt solution is 19.31 g.</div>
		</li>
		<li data-sub-note-item="2-4">
		<div class="lab-step">Repeat the calculation to obtain the mass of 20 mL of salt solution that was measured using the 10-mL pipette and the 200-mL volumetric flask.<b> Note:</b> Generally speaking, volumetric measurements are more accurate when using a volumetric flask.</div>
		</li>
		<li data-sub-note-item="2-5">
		<div class="lab-step">Look at the accuracy of the other methods compared to the volumetric flask in terms of percent error. Percent error is calculated by subtracting the theoretical value from the experimental value, then dividing by the theoretical value times 100.
		<ul>
			<li><img src="https://www.jove.com/CDNSource/lm/labs/41/41_Procedure_1b.jpg" /></li>
		</ul>
		</div>
		</li>
		<li data-sub-note-item="2-6">
		<div class="lab-step">Use the volumetric flask measurement as the theoretical value to determine the percent error for the other volume measurement methods. As expected, the volume measurement that uses the markings on the beaker is the least accurate.<strong> Note: </strong>We also know this because the known density of pure water is 1 g/mL. Thus, 20 mL of pure water weighs 20 g. The density of the salt solution must be higher than 20 g since salt was added to the water.</div>
		</li>
		<li data-sub-note-item="2-7">
		<div class="lab-step">Calculate the density of the salt solution using the volumetric flask measurement. Divide the mass of the solution by the volume of the solution. Thus, the density of the salt solution is 1.053 g/mL.</div>
		</li>
		<li data-sub-note-item="2-8">
		<div class="lab-step">Compare the calculated density of the salt solution to the density of the egg. The volume calculated using the displacement of water in a beaker was found to be 61.14 cm<sup>3</sup> or 61.14 mL. The weight of the egg was measured to be 60.15 g, so its density is 0.9838 g/mL. The disparity between the density of the egg and the density of the salt solution arises from error introduced in both calculations, primarily due to volume measurement readings.</div>
		</li>
	</ul>
	</li>
</ol>

Accuracy, Precision, Uncertainty, and Significant Figures - Procedure

Techniques de laboratoire

Source: Smaa Koraym at Johns Hopkins University, MD, USA

	Determining the Density of an EggExpand
	Density is a measure of how compact a substance or ...

Eusociality and Division of Labor

<ol class="note-items"><li data-note-item="1" data-parent-collapse="">Simulating Eusocial and Solitary Behavior
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="1-1"><div class="lab-step">Note: In this simulation, you will portray either a eusocial or solitary animal. The goal of this simulation is to maximize your fitness by reproducing as many offspring as possible during the allotted five minutes. To do this, you must forage for resources and reproduce within the constraints of your assigned role.
</div></li><li data-sub-note-item="1-2"><div class="lab-step">Assuming a class size of 10, 4 individuals should form the solitary, or the carpenter bee group, and the remaining 6 students should form the eusocial, or the honeybee group. Note: The eusocial honeybee group will include one queen, one drone, and four workers. The queen and the drone will reproduce and protect the resources, while the workers will forage and steal resources. The solitary carpenter bee students must perform all of the tasks in this activity, with the exception of reproduction, by themselves.
</div></li><li data-sub-note-item="1-3"><div class="lab-step">Store your resources for reproduction in the nest bowl provided by your instructor. These resources are represented by assorted beans that can be collected by foraging in the environment buckets or by stealing from other nests.
</div></li><li data-sub-note-item="1-4"><div class="lab-step">The blue cups are male and the red cups are female, and they will be used to produce offspring. This is done by combining all four bean types in one red or blue cup to symbolize the resources needed to reproduce, and then stacking one completed cup inside a cup of the opposite color that also contains one of each bean type, to simulate a mating that produces two-cup offspring, one from each parent.
</div></li><li data-sub-note-item="1-5"><div class="lab-step">To reproduce, the solitary students will need to seek out another solitary student with an opposite-colored cup. Conversely, the eusocial queen and drone always reproduce with each other. HYPOTHESES: The hypotheses for this lab activity are based on the possible benefits of eusocial groups over solitary individuals. The alternate hypothesis could be that one group, either eusocial or solitary, will have an advantage over the other, given the ecological constraints, and this will be reflected in the number of offspring per capita. The null hypothesis might be that there will be advantage conferred by either of the strategies.
</div></li><li data-sub-note-item="1-6"><div class="lab-step">If you are a worker in the honeybee group or a solitary student in the carpenter bee group, walk to the other side of the room to search through the rice on the foraging side of the room for one bean and bring the bean back to your bowl on the nest side of the room. Note: Even though this activity has a 5-minute time limit, running is not permitted. 
</div></li><li data-sub-note-item="1-7"><div class="lab-step">If a solitary student is not present at a neighboring bowl, you can try to steal one bean at a time, using a cup to scoop up the bean without touching the bean or the bowl with anything but the cup. You must immediately stop trying to steal if the solitary student makes it back to their bowl before you finish stealing. Note: Neighbors cannot steal from eusocial nests because the queen and drone do not leave their nest.
</div></li><li data-sub-note-item="1-8"><div class="lab-step">You can create offspring at any time during the activity. Remember to label each cup that is contributed to an offspring with your name to keep track of your reproduction.  Note: Eusocial groups produce two offspring for their group every time they reproduce, while solitary students produce only one offspring per reproductive coupling.
</div></li></ul></li><li data-note-item="2" data-parent-collapse="">Results
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="2-1"><div class="lab-step">If you were a solitary carpenter bee, record the number of offspring you produced in the appropriate row of the table. <a href="https://www.jove.com/CDNSource/lm/labs/36/Table_1_Eusociality_and_division_of_labor.xlsx" style="display:block;margin:20px;" target="_blank">Click Here to download Table 1</a>
</div></li><li data-sub-note-item="2-2"><div class="lab-step">If you were a part of the eusocial honeybee group, record the number of offspring produced by your queen and drone.
</div></li><li data-sub-note-item="2-3"><div class="lab-step">To calculate the fitness for a solitary carpenter bee student, simply count the number of offspring that the student produced.
</div></li><li data-sub-note-item="2-4"><div class="lab-step">To calculate the fitness for a eusocial honeybee student, divide the number of offspring produced by the queen and drone by the number of members in the group, in this case 6, to get a per-student fitness value.
</div></li><li data-sub-note-item="2-5"><div class="lab-step">When each student has calculated their respective fitness value, calculate the average number of offspring produced for each social category and plot these as a bar graph. <a href="https://www.jove.com/CDNSource/lm/labs/36/Table_2_Eusociality_and_division_of_labor.xlsx" style="display:block;margin:20px;" target="_blank">Click Here to download Table 2</a>
</div></li><li data-sub-note-item="2-6"><div class="lab-step">Next, use Hamilton&#39;s equation to analyze the data. To do this, set r equal to the degree of relatedness, B to the class average eusocial fitness, and C to the class average solitary fitness.  r * B > C
</div></li><li data-sub-note-item="2-7"><div class="lab-step">Use these results to determine if altruistic behavior should persist in your eusocial honeybee group. Discuss the variables in Hamilton&#39;s equation that may contribute to this observation. Consider circumstances under which you would expect to see different results. 
</div></li></ul></li></ol>

Eusocialité et division du travail

Simulating Eusocial and Solitary Behavior
ExpandNote: In this simulation, you will portray either a eusocial or solitary animal. The goal of this ...

Ecologie

Community Diversity

<ol class="note-items"><li data-note-item="1" data-parent-collapse="">Measuring Biodiversity in Areas with Different Disturbance Regimes
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="1-1"><div class="lab-step">NOTE: In this experiment, you will compare the biodiversity in a less disturbed area against a more highly disturbed area. HYPOTHESES: The experimental hypothesis could be that a less disturbed area will contain a greater diversity of species than a highly disturbed area. The null hypothesis could be that there will be no difference in diversity between less disturbed and highly disturbed areas. 
</div></li><li data-sub-note-item="1-2"><div class="lab-step">To begin, divide into groups of 2-4 and collect a hula hoop, ball, measuring tape, set of printed tables, 10 utility flags, and an ID guide from the front of the class.
</div></li><li data-sub-note-item="1-3"><div class="lab-step">Additionally, collect a shovel and 10 collecting bottles for the soil sampling exercise.
</div></li><li data-sub-note-item="1-4"><div class="lab-step">Once in the field, your instructor will show you the two habitats you will study - choose one habitat to begin.
</div></li><li data-sub-note-item="1-5"><div class="lab-step">Place one flag in each of four corners to form a rectangular sampling area.
</div></li><li data-sub-note-item="1-6"><div class="lab-step">Measure the length and width of the sampling area in meters, and then multiply the two numbers to determine the area.
</div></li><li data-sub-note-item="1-7"><div class="lab-step">Standing in the middle of the sampling area, throw a tennis ball into the air, and then Mark the location where it lands with a flag.
</div></li><li data-sub-note-item="1-8"><div class="lab-step">Repeat this random throw four additional times to determine all five of your random sampling points.
</div></li><li data-sub-note-item="1-9"><div class="lab-step">Keeping your flag at the center, place a hula hoop around it. The area within the hula hoop is a quadrat.
</div></li><li data-sub-note-item="1-10"><div class="lab-step">Identify all of the different species in the quadrat and record them as species A, B, and so on in Table 1, provided by your instructor.
</div></li><li data-sub-note-item="1-11"><div class="lab-step">Once all of the plants have been recorded, use a shovel to collect one cup of soil from each of the sites and put the samples bottles labeled with your names and the site name and quadrat number.
</div></li><li data-sub-note-item="1-12"><div class="lab-step">Repeat the plant identification and soil sampling for the remaining four quadrats in the first habitat, recording your observations in Table 1.
</div></li><li data-sub-note-item="1-13"><div class="lab-step">Once you have completed recording in the first habitat, move on to the second field, again marking out a rectangular sampling area.
</div></li><li data-sub-note-item="1-14"><div class="lab-step">Repeat the random placement of quadrats using the tennis ball, and then record the species present in each quadrat in Table 2. 
</div></li><li data-sub-note-item="1-15"><div class="lab-step">Finally, collect one cup of soil from each of the disturbed habitats&#39; quadrats, for a total of five cups from the disturbed and five cups from the undisturbed habitats.
</div></li></ul></li><li data-note-item="2" data-parent-collapse="">Measuring Biodiversity Along a Transect
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="2-1"><div class="lab-step">NOTE: The next part of the study will test for edge effects, or a change along a gradient from where one ecosystem type meets another to the core habitat of the ecosystem. HYPOTHESES: The experimental hypothesis is that there will be a greater diversity of species closer to the edge of the ecosystem than in the center, or core, of the ecosystem. The null hypothesis is that there is no change in diversity along the transect from edge to core habitat.
</div></li><li data-sub-note-item="2-2"><div class="lab-step">Place a flag at the perimeter of the field where it meets another habitat, like a forest or parking lot.
</div></li><li data-sub-note-item="2-3"><div class="lab-step">Extend a tape measure towards the center of the field, perpendicular to the edge of the field. This will be the transect.
</div></li><li data-sub-note-item="2-4"><div class="lab-step">Place a flag at the zero meter of the transect (the edge of the other habitat) then place additional flags at 10 m, 20 m, 30 m, and 40 m into the core of the habitat for a total of five flagged locations.
</div></li><li data-sub-note-item="2-5"><div class="lab-step">Starting at the 0 m point along the transect, place the hula hoop at the flagged location. Record the species present in the quadrat in Table 4.
</div></li><li data-sub-note-item="2-6"><div class="lab-step">Now repeat the quadrant placement and species recording at the 10 m, 20 m, 30 m, and 40 m marks.
</div></li><li data-sub-note-item="2-7"><div class="lab-step">Next, place two more transects from different starting points at the perimeter of the field extending into the core area.
</div></li><li data-sub-note-item="2-8"><div class="lab-step">Mark the 10-meter points along these transects, and again use these as markers to place quadrats. Record the species found in each of these quadrats in Table 4.
</div></li></ul></li><li data-note-item="3" data-parent-collapse="">Processing the Soil Samples
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="3-1"><div class="lab-step">HYPOTHESES: The experimental hypothesis is that the two landscapes under different disturbance regimes will differ in their soil composition and pH. The null hypothesis is that there will be no difference in the soil composition or pH between the two sites. 
</div></li><li data-sub-note-item="3-2"><div class="lab-step">To begin, remove soil from one bottle of the first site sampled and fill the pH color compartment of the soil sample kit to the soil fill line.
</div></li><li data-sub-note-item="3-3"><div class="lab-step">Pour the pH test capsule into the test chamber, then fill the capsule with distilled water until it reaches the water fill line.
</div></li><li data-sub-note-item="3-4"><div class="lab-step">Place the cap on the compartment and shake it.
</div></li><li data-sub-note-item="3-5"><div class="lab-step">Allow the color to develop for about a minute, and then compare the soil to the color chart to determine the pH.
</div></li><li data-sub-note-item="3-6"><div class="lab-step">Repeat the pH analysis for the second sampled site, filling out Table 3 for the recorded pH.
</div></li><li data-sub-note-item="3-7"><div class="lab-step">To process the soil samples for nitrogen, phosphorus, and potassium, remove 20 mL of soil from the bottle of the first site sampled.
</div></li><li data-sub-note-item="3-8"><div class="lab-step">Place the soil in a clean container with 100 mL of distilled water.
</div></li><li data-sub-note-item="3-9"><div class="lab-step">Repeat this process for the second site, labeling each container, and then allow them to sit for one hour.
</div></li><li data-sub-note-item="3-10"><div class="lab-step">After one hour, use a dropper to fill each of the nitrogen, phosphorous, and potassium comparators to the fill line with solution from the first sampled site.
</div></li><li data-sub-note-item="3-11"><div class="lab-step">Add the appropriate capsule to each of the comparators for each chemical test.
</div></li><li data-sub-note-item="3-12"><div class="lab-step">Cap and shake the comparators thoroughly, and then compare the solution in the test chamber to the color chart, recording the results as the appropriate number on the scale into Table 3.
</div></li><li data-sub-note-item="3-13"><div class="lab-step">Repeat the nitrogen, phosphorous, and potassium tests for each of the sampled sites. NOTE: Rinse the comparator thoroughly between samples
</div></li></ul></li><li data-note-item="4" data-parent-collapse="">Results
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="4-1"><div class="lab-step">To calculate the Shannon-Weiner Diversity for each of the observed sites, first open a new Excel spreadsheet.
</div></li><li data-sub-note-item="4-2"><div class="lab-step">Label cell A1 'species name', and cell B1 'total count'.
</div></li><li data-sub-note-item="4-3"><div class="lab-step">Starting from the second row and in column A, fill in the sheet for each species found in the first site, using the data recorded in Table 1.
</div></li><li data-sub-note-item="4-4"><div class="lab-step">Calculate the total number of each species found in the entire sampling effort and record this in the B column of the Excel spreadsheet.
</div></li><li data-sub-note-item="4-5"><div class="lab-step">Now, label cell G1 'total count of all species', and in cell H1, write a formula, or highlight the appropriate cells to sum all of the count values entered in column B: = SUM(B2: BX)
</div></li><li data-sub-note-item="4-6"><div class="lab-step">Label cell C1 'proportion of each species' and in cell C2, type the formula for the proportion of the total of each species at the site. = B2/H$1
</div></li><li data-sub-note-item="4-7"><div class="lab-step">Drag this formula down for each row of data represented in column B.
</div></li><li data-sub-note-item="4-8"><div class="lab-step">Label cell D1 'natural log proportion of species' and in cell D2, type the formula for the natural log of the proportion of species at the site. =LN(C2)
</div></li><li data-sub-note-item="4-9"><div class="lab-step">Drag this formula down for each row of data represented in column C.
</div></li><li data-sub-note-item="4-10"><div class="lab-step">Add the formula into cell E1 for the proportion of species multiplied by the natural log of the proportion of species: ps* ln ps
</div></li><li data-sub-note-item="4-11"><div class="lab-step">In cell E2, type the formula multiplying the proportion of species by the natural log of the proportion of species at each site, and then drag this formula down for each row of data represented in column D. = C2 * D2 
</div></li><li data-sub-note-item="4-12"><div class="lab-step">Label cell G2 as 'sum of ps * ln ps', and then, in cell H2, type a formula summing all of the values in column E. = SUM(E3 - EX) 
</div></li><li data-sub-note-item="4-13"><div class="lab-step">Label cell G3 'Shannon-Weiner Index', and in cell H3, enter the formula for the Shannon-Weiner Diversity Index. = (EXP - 1 * H2) NOTE: This is the calculated Shannon-Weiner Diversity Index for the first sampled site, and will be used for comparison between the two sites.
</div></li><li data-sub-note-item="4-14"><div class="lab-step">Repeat the data analysis in a new sheet using the data collected for the second site, which was recorded in Table 2. NOTE: Areas with greater index values are considered to have greater species diversity. Note whether you see differences between your sites.
</div></li><li data-sub-note-item="4-15"><div class="lab-step">Repeat the Shannon-Weiner Diversity calculations using a total count of all the species at each distance along the transect, then create a table of all of these values in a new Excel sheet.
</div></li><li data-sub-note-item="4-16"><div class="lab-step">Click on the Data tab in Excel, and then on the 'Data Analysis' button.
</div></li><li data-sub-note-item="4-17"><div class="lab-step">Select 'Regression' and click 'Okay'.
</div></li><li data-sub-note-item="4-18"><div class="lab-step">For the Input Y Range, highlight the Shannon-Weiner Diversity values, and for the Input X range, highlight the distance values.
</div></li><li data-sub-note-item="4-19"><div class="lab-step">Select an output location for the regression results and click 'Okay'.
</div></li><li data-sub-note-item="4-20"><div class="lab-step">Check the P-value box in the intercept row to see if there is a significant correlation between distance from edge to core habitat and biodiversity. NOTE: A value of less than 0.05 rejects the null hypothesis of no change in diversity along the transect, while a value greater than 0.05 does not reject the null hypothesis.
</div></li><li data-sub-note-item="4-21"><div class="lab-step">Next, to perform t-tests for determining soil composition differences between sites, open a new Excel spreadsheet.
</div></li><li data-sub-note-item="4-22"><div class="lab-step">In cell A1, type 'Site 1:pH', and in cell B1, type 'Site 2:pH'.
</div></li><li data-sub-note-item="4-23"><div class="lab-step">Fill in cells A2 through A6 and cells B2 through B6 with the soil pH collected in the disturbed and undisturbed sites, respectively.
</div></li><li data-sub-note-item="4-24"><div class="lab-step">Click the Data tab in Excel and then select 'Data Analysis'.
</div></li><li data-sub-note-item="4-25"><div class="lab-step">Now scroll down and select 't-Test: Two-Sample Assuming Equal Variances' and select 'Okay'.
</div></li><li data-sub-note-item="4-26"><div class="lab-step">Click the drop down next to Variable 1 Range and highlight cells A2 through A6 in the spreadsheet, then click the dropdown next to Variable 2 Range and highlight cells B2 through B6 in the spreadsheet.
</div></li><li data-sub-note-item="4-27"><div class="lab-step">In the box for hypothesized mean difference, type zero as our null hypothesis. This means that there is no difference between the two disturbance regimes.
</div></li><li data-sub-note-item="4-28"><div class="lab-step">Leave the Labels box unchecked and set the alpha value to 0.05.
</div></li><li data-sub-note-item="4-29"><div class="lab-step">Select 'Output Range', and in the box, click an empty space in the spreadsheet.
</div></li><li data-sub-note-item="4-30"><div class="lab-step">Click 'Okay'. A table of t-Test results should be outputted in the spreadsheet.
</div></li><li data-sub-note-item="4-31"><div class="lab-step">The relevant data are the means for each of the sites and the alpha value. If this second value is less than our alpha value of 0.05, we can reject the null hypothesis that there is no difference in pH between the two sites, and the hypothesis that disturbed versus undisturbed sites differ in their pH value would gain support. If this value is greater than 0.05, however, we may not reject our null hypothesis.
</div></li><li data-sub-note-item="4-32"><div class="lab-step">Repeat this analysis for each of the other three soil variables, creating a new spreadsheet for each of the phosphorus, potassium, and nitrogen elements. 
</div></li><li data-sub-note-item="4-33"><div class="lab-step">Note whether your pH and nutrient level results were different in each condition, and discuss with your group how this might affect the community and diversity in the different sites.
</div></li></ul></li></ol>

Community Diversity: Measuring Biodiversity in Different Areas - Procedure

Diversité communautaire

Measuring Biodiversity in Areas with Different Disturbance Regimes
ExpandNOTE: In this experiment, you will compare the biodiversity in a less disturbed ...

Genetics of Organisms

<ol class="note-items"><li data-note-item="1" data-parent-collapse="">REF and WEF Fly Genetics
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="1-1"><div class="lab-step">NOTE: At your station, you should have four vials of flies. They will be labeled as male or female. They will also be labeled with the notation REF for red-eyed flies or WEF for white-eyed flies. The female vial should also be labeled virgin as these flies should be unmated for the purpose of this experiment.
</div></li><li data-sub-note-item="1-2"><div class="lab-step">Make sure you have around five flies in each vial. NOTE: You will perform crosses using these flies to determine if red or white eyes is dominant and if the trait is sex-linked. You should also have two fly anesthesia wands, a paint brush, magnifying glass, fly anesthetic, some empty fly vials, and a sheet of white paper.
</div></li><li data-sub-note-item="1-3"><div class="lab-step">Draw a line in the middle of the paper to make a male side and a female side.
</div></li><li data-sub-note-item="1-4"><div class="lab-step">Dip the fly anesthesia wand into the solution and insert it into the red-eyed female vial until the flies stop moving.
</div></li><li data-sub-note-item="1-5"><div class="lab-step">Then, dip the same wand into the white-eyed male vial until these flies are also anesthetized.
</div></li><li data-sub-note-item="1-6"><div class="lab-step">Tap the flies from the two vials onto the sheet - Females on one side and males on the other.
</div></li><li data-sub-note-item="1-7"><div class="lab-step">Check to make sure that all the flies from the female vial are female and likewise, confirm that the male flies are male.  NOTE: Males are slightly smaller and have a darker solid pigment on the end of their abdomen. Females are larger and have stripes rather than a solid spot.
</div></li><li data-sub-note-item="1-8"><div class="lab-step">If there are any male flies in the female vial, obtain a new vial as these females likely have sperm from males from their own strain and are unusable.
</div></li><li data-sub-note-item="1-9"><div class="lab-step">Now, move the five red-eyed females and five white-eyed males into a new vial using the paintbrush.
</div></li><li data-sub-note-item="1-10"><div class="lab-step">Label this vial to indicate that this is a cross between red-eyed females and white-eyed males. HYPOTHESES: Use Punnett squares to formulate hypotheses for this experiment. Consider what you will see in a few days if the white allele is dominant and there is no effect of parental sex. What if red is dominant? Under the potential offspring genotype in each box, write the expected phenotype.
</div></li><li data-sub-note-item="1-11"><div class="lab-step">To set up the reverse cross, again dip the fly anesthesia wand into the solution and insert it this time into the white-eyed female vial and then the red-eyed male vial until all the flies have stopped moving.
</div></li><li data-sub-note-item="1-12"><div class="lab-step">Tap the flies onto a sheet of white paper and check to make sure that all the flies from the female vial are female and likewise with the male flies.
</div></li><li data-sub-note-item="1-13"><div class="lab-step">Now, move the five white-eyed females and five red-eyed males into a new vial using the paintbrush.
</div></li><li data-sub-note-item="1-14"><div class="lab-step">Label this vial to indicate that this is a cross between white-eyed females and red-eyed males.
</div></li><li data-sub-note-item="1-15"><div class="lab-step">Finally, place the two tubes containing the new crosses into a rack for incubation at room temperature. NOTE: After about three days, larvae should be moving around in the vial.
</div></li><li data-sub-note-item="1-16"><div class="lab-step">Remove the 10 adult flies and dispose of them into the morgue tube containing 70% ethanol.
</div></li><li data-sub-note-item="1-17"><div class="lab-step">Now, put the tubes back in the rack and let the larvae mature until they reach the adult stage in up to two weeks.
</div></li><li data-sub-note-item="1-18"><div class="lab-step">Once all of the larvae from these crosses have matured to adulthood, anesthetize the flies in one of the tubes using the wand.
</div></li><li data-sub-note-item="1-19"><div class="lab-step">Then, on a piece of white paper, sort the flies by sex and phenotype and then record these data.
</div></li><li data-sub-note-item="1-20"><div class="lab-step">Now, repeat this process and tally the sexes and phenotypes for the second cross (steps 1 &#8211; 18).
</div></li><li data-sub-note-item="1-21"><div class="lab-step">Finally, once you have counted all of your flies, dispose of them in the morgue vial.
</div></li></ul></li><li data-note-item="2" data-parent-collapse="">Results
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="2-1"><div class="lab-step">To begin investigating your results, first compare the data you collected with the hypothesis you made using the Punnett squares.
</div></li><li data-sub-note-item="2-2"><div class="lab-step">Did your data match the simple Punnett square hypothesis where red or white is dominant and there is no effect of sex? Compare your data with other lab groups.
</div></li><li data-sub-note-item="2-3"><div class="lab-step">If your data does not match what your Punnett squares predicted, does this indicate that the gene may be sex-linked?
</div></li><li data-sub-note-item="2-4"><div class="lab-step">If the red gene were dominant and sex-linked, when we cross red-eyed females with white-eyed males, all of the offspring would have red eyes. Assuming all of the females were homozygous for the color allele, does this match your data for the first cross?
</div></li><li data-sub-note-item="2-5"><div class="lab-step">If white were dominant and the gene were sex-linked, we would see the exact opposite. So all of the flies would have white eyes. From your data, can you conclude from your first cross whether red or white is dominant?
</div></li><li data-sub-note-item="2-6"><div class="lab-step">When the reciprocal cross of white-eyed females and red-eyed males is performed, if the red phenotype is dominant, all of the females would be red and all of the males would be white. This would also confirm that the gene is specifically x-linked because white-eyed females could then only be produced in crosses with white-eyed males. Did your second cross produce any white-eyed females?
</div></li><li data-sub-note-item="2-7"><div class="lab-step">Finally, if the gene were x-linked and white was dominant, crossing white-eyed females with red-eyed males would result in all of the offspring having white eyes. Does this hypothesis fit with your second cross?
</div></li><li data-sub-note-item="2-8"><div class="lab-step">Look over your data and conclude which of the hypotheses best fits the patterns you found in your crosses. If your data does not fit with any of these, hypothesize why this might be the case.
</div></li></ul></li></ol>

Genetics of Organisms: REF and WEF Fly Genetics - Procedure

Génétique des organismes

REF and WEF Fly Genetics
ExpandNOTE: At your station, you should have four vials of flies. They will be labeled as male or female. They will also be ...

Génétique

Evolutionary Relationships

<ol class="note-items"><li data-note-item="1" data-parent-collapse="">Forming an Evolutionary Hypothesis
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="1-1"><div class="lab-step">NOTE: A cladogram is an important tool for forming an evolutionary hypothesis. A cladogram is a tree-shaped chart used to depict the hypothetical genealogical relationships between species. The tips or leaves of the chart represent specific species and the branches of the tree are different lengths. The different lengths represent the degree of change between each of the species. The common ancestor of all of the species that a specific line branches from is located at a node, where the branches intersect. Species that share a node are called a sister group.
</div></li><li data-sub-note-item="1-2"><div class="lab-step">To begin, look at the provided blank cladogram and make a hypothesis about where the assigned animals should be placed on the tree. If a blank cladogram has not been provided please <a target="_blank" href="/files/ftp_upload/10562/Blank_Cladogram.png">download one here</a>.
</div></li><li data-sub-note-item="1-3"><div class="lab-step">Next, observe the image of the fossilized animal.
</div></li><li data-sub-note-item="1-4"><div class="lab-step">Using the morphology, or physical characteristics, of the fossil, make a hypothesis about where on your cladogram it should be placed. Add a new line or mark to indicate your proposed position for the fossil.
</div></li></ul></li><li data-note-item="2" data-parent-collapse="">Comparing Gene Sequences Using BLAST
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="2-1"><div class="lab-step">NOTE: Historically, cladograms have been constructed through the comparison of morphology. Now, genetic sequences can also be compared between species of interest to construct cladograms. DNA sequences are not usually preserved in fossils, so for this lab you will use the BLAST database to compare the DNA sequences of living species that are closely related to the fossil to thousands of other living species.
</div></li><li data-sub-note-item="2-2"><div class="lab-step">Before beginning this lab, your instructor will have downloaded the three preserved gene sequences to a folder on your desktop.
</div></li><li data-sub-note-item="2-3"><div class="lab-step">Navigate to the BLAST homepage, which the instructor should have left open in your browser, and click on Saved Strategies from the menu at the top of the page.
</div></li><li data-sub-note-item="2-4"><div class="lab-step">Click Open on the Evolutionary_Relationships_Gene1.txt file.
</div></li><li data-sub-note-item="2-5"><div class="lab-step">Then, click View to go to the Standard Nucleotide BLAST search page. You should be able to see the DNA sequence in the Query Sequence box at the top-right of the screen.
</div></li><li data-sub-note-item="2-6"><div class="lab-step">Scroll to the bottom of the screen and click the BLAST button. Note: It will take a few moments to process and analyze the data. 
</div></li><li data-sub-note-item="2-7"><div class="lab-step">When the data has been processed, a graphic summary will appear.  NOTE: Your query sequence is represented by the blue line at the top of the box. Each of the lines below the blue line represents another sequence in the BLAST database that matches your query. The length and location of these bars represent where and how much of the sequence match up to the query. The color of the bar represents its score, or how identical the sequence is to the query. Below the graphic summary is the Sequences producing significant alignments list, which contains descriptions of the DNA sequences retrieved from the database that most closely align with the query sentence. These are listed in descending order, from the most similar at the top to the least similar at the bottom. On the right, there are several statistics on how closely related each database sequence is to the experimental sequence. The higher the Max, Total, Query Coverage, and Identity scores are, the more similar the query and retrieved sequences are to each other. Similarly, the lower the E value number, the less likely the sequences match was found by random chance and more significantly the alignment is accurate. An E value of 0 indicates a highly significant match.
</div></li><li data-sub-note-item="2-8"><div class="lab-step">Click on the name of the description of the most similar alignment listed. This will take you further down the page to the exact DNA sequence alignment between the retrieved sequence and the query sequence.
</div></li><li data-sub-note-item="2-9"><div class="lab-step">Click on the Sequence ID number. This will open a new tab with more specific information on the retrieved gene sequence.
</div></li><li data-sub-note-item="2-10"><div class="lab-step">Identify and record the scientific and common names of the organism, which should be listed next to Source.
</div></li><li data-sub-note-item="2-11"><div class="lab-step">Identify and record the protein that the gene codes for, which should be listed next to Definition.
</div></li><li data-sub-note-item="2-12"><div class="lab-step">Close the tab and hit Back to return to the Sequences producing significant alignments list.
</div></li><li data-sub-note-item="2-13"><div class="lab-step">Then, repeat steps 7 &#8211; 9 for the next most similar sequences.
</div></li><li data-sub-note-item="2-14"><div class="lab-step">After collecting several species names, return to the Sequences producing significant alignments list and click Select: All to check all of the boxes next to the names of each listed alignment sequence.
</div></li><li data-sub-note-item="2-15"><div class="lab-step">Click on Distance of tree results to create a phylogram based on the similarity of all of the BLAST result gene sequences to the query gene sequence.  Note: Your query fossil relative sequence will be highlighted in yellow.
</div></li><li data-sub-note-item="2-16"><div class="lab-step">Record your sequence&#8217;s location in relation to the other taxon groups shown in the tree.
</div></li><li data-sub-note-item="2-17"><div class="lab-step">Finally, return to the Saved Strategies tab and upload the next saved gene sequence.
</div></li><li data-sub-note-item="2-18"><div class="lab-step">Query the remaining two fossil relative DNA sequences as previously demonstrated (steps 1 &#8211; 16).
</div></li></ul></li><li data-note-item="3" data-parent-collapse="">Data Analysis
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="3-1"><div class="lab-step">Based on your gene sequence results, come up with a second hypothesis about where your fossil specimen fit in the original cladogram.
</div></li><li data-sub-note-item="3-2"><div class="lab-step">Compare this placement with your first hypothesis.
</div></li><li data-sub-note-item="3-3"><div class="lab-step">Compare your tree with your classmates&#8217;. If any of your classmates put the fossil on a different branch, ask them how they came to that decision.
</div></li></ul></li></ol>

Evolutionary Relationships: Using BLAST to Test Evolutionary Hypotheses - Procedure

Relations évolutives

Forming an Evolutionary Hypothesis
ExpandNOTE: A cladogram is an important tool for forming an evolutionary hypothesis. A cladogram is a tree-shaped chart ...

Evolution

Microbial and Fungal Diversity

<ol class="note-items"><li data-note-item="1" data-parent-collapse="">Examining Microbial Colony Structures
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="1-1"><div class="lab-step">To begin, collect your allocated culture plates and then remove the Parafilm and lid from one of them.
</div></li><li data-sub-note-item="1-2"><div class="lab-step">Place the uncovered plate under a dissecting microscope and then observe the individual communities within each quadrant of the plate.
</div></li><li data-sub-note-item="1-3"><div class="lab-step">As the colonies are identified, fill out the observed colony properties in the appropriate column in the table.  <a href="https://www.jove.com/CDNSource/lm/labs/28/Table_1_Microbial_diversity.xlsx" style="display:block;margin:20px;" target="__blank">Click Here to download Table 1</a>
</div></li><li data-sub-note-item="1-4"><div class="lab-step">Then, repeat the observations for each of the other two bacterial species.
</div></li><li data-sub-note-item="1-5"><div class="lab-step">To perform Gram staining of your three bacterial species, first label the ends of three microscope slides with the initials of each bacteria species, your initials, and the date. HYPOTHESES: In this experiment, the experimental hypothesis might be that it is possible to elucidate different bacterial species and shapes using Gram staining, and that Gram-positive bacteria will stain purple with crystal violet whereas Gram-negative bacteria will appear pink due to the safranin counterstain. The null hypothesis could be that all of the bacterial types will retain both stains equally, and staining will not help elucidate their species or shape.
</div></li><li data-sub-note-item="1-6"><div class="lab-step">To begin the first stain, attach a clip to the slide for ease of handling. For each bacterial smear, remember to be sure to use a cleaned and flame-sterilized inoculating loop.
</div></li><li data-sub-note-item="1-7"><div class="lab-step">Place two loopfuls of sterile distilled water onto the center of the slide.
</div></li><li data-sub-note-item="1-8"><div class="lab-step">After sterilizing the loop again, cool the loop by touching an uninoculated portion of the agar several times.
</div></li><li data-sub-note-item="1-9"><div class="lab-step">Then, remove a small amount of culture from an isolated colony and mix it with the water on the slide.
</div></li><li data-sub-note-item="1-10"><div class="lab-step">Allow the slide to dry at room temperature and heat-fix the smear by quickly passing it through a flame.
</div></li><li data-sub-note-item="1-11"><div class="lab-step">Once dry, pipette several drops of crystal violet onto the slide and let it sit for two to three minutes.
</div></li><li data-sub-note-item="1-12"><div class="lab-step">Carefully rinse the slide with distilled water by aiming the direct flow towards the top of the slide, allowing the water to gently flow down. Do not aim the water flow directly at the smear.
</div></li><li data-sub-note-item="1-13"><div class="lab-step">Next, cover the slide with Gram&#39;s iodine, leave it to sit again for two minutes, and then gently rinse with distilled water.
</div></li><li data-sub-note-item="1-14"><div class="lab-step">Decolorize the slide with 95% ethanol until stain no longer washes away.
</div></li><li data-sub-note-item="1-15"><div class="lab-step">Immediately, rinse the slide with distilled water. This will limit over-decolorizing.
</div></li><li data-sub-note-item="1-16"><div class="lab-step">Then, add several drops of safranin counterstain and leave for 30 s. This will stain any Gram-negative cells present.
</div></li><li data-sub-note-item="1-17"><div class="lab-step">Gently rinse the slide with distilled water and blot dry with absorbent paper.
</div></li><li data-sub-note-item="1-18"><div class="lab-step">After staining the other two slides in the same manner (steps 6 &#8211; 17), observe each with a microscope.
</div></li><li data-sub-note-item="1-19"><div class="lab-step">Use a low power objective first to make coarse adjustments. When you find an ideal section, move on to the higher magnifications.
</div></li><li data-sub-note-item="1-20"><div class="lab-step">After further imaging and adjusting the smear with a medium power objective, add immersion oil directly to the smear. NOTE: The oil is needed for high power objectives that will provide the best micrographs.
</div></li><li data-sub-note-item="1-21"><div class="lab-step">Now, use colored pencils to draw the observed bacteria in the appropriate magnification circles and fill in the observed characteristics in the appropriate column, noting the bacteria&#39;s shape and whether it is Gram-positive, identified by darker purple staining, or Gram-negative, identified with pink staining. <a href="https://www.jove.com/CDNSource/lm/labs/28/Table_2_Microbial_diversity.xlsx" style="display:block;margin:20px;" target="__blank">Click Here to download Table 2</a>
</div></li><li data-sub-note-item="1-22"><div class="lab-step">Finally, repeat the observation, drawing, and characterization for the other two stained bacterial slides.
</div></li></ul></li><li data-note-item="2" data-parent-collapse="">Examining Fungal Structures
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="2-1"><div class="lab-step">Remove the <em>S. cerevisiae</em> plate from the incubator and place a drop of water onto a microscope slide.
</div></li><li data-sub-note-item="2-2"><div class="lab-step">Using a sterilized inoculating loop, smear a film of yeast into the drop of water and place a cover slip over the slide.
</div></li><li data-sub-note-item="2-3"><div class="lab-step">Place the slide under the microscope at the lowest magnification, increasing the magnification to the oil immersion setting to see the individual yeast cells.
</div></li><li data-sub-note-item="2-4"><div class="lab-step">Observe the general shape and structure of the yeast and identify any cells that are undergoing asexual reproduction by budding.
</div></li><li data-sub-note-item="2-5"><div class="lab-step">Now, draw the cells in the appropriate magnification circles.
</div></li><li data-sub-note-item="2-6"><div class="lab-step">When you are done observing the yeast, replace the <em>S. cerevisiae</em> slide with a prepared Ascomycetes apothecium slide and set the microscope to the lowest magnification.
</div></li><li data-sub-note-item="2-7"><div class="lab-step">Using colored pencils, draw the structures at low and high magnifications, including the asci and ascospores.
</div></li><li data-sub-note-item="2-8"><div class="lab-step">Finally, place a button mushroom, <em>Agaricus bisporus</em>, under the dissecting microscope and draw the features, including the pileus, or cap, the gills, and the stipe, or stalk.
</div></li></ul></li><li data-note-item="3" data-parent-collapse="">Results
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="3-1"><div class="lab-step">Using the coloring of the bacteria recorded in the table, determine which species are Gram-positive and which are Gram-negative.
</div></li><li data-sub-note-item="3-2"><div class="lab-step">Then, look at the shapes recorded in the table to determine which bacterial species are bacillus, coccus, or spirillum.
</div></li><li data-sub-note-item="3-3"><div class="lab-step">Next compare your illustrations of the yeast cells to your illustrations of the bacterial cells. NOTE: Yeast from the Ascomycetes phylum, such as <em>S. cerevisiae</em>, can reproduce asexually, which can be observed through the budding of the cells under a microscope.
</div></li><li data-sub-note-item="3-4"><div class="lab-step">Record any observations of yeast cells budding.  NOTE: Ascomycetes can also reproduce sexually via mitosis and haploid spore formation.
</div></li><li data-sub-note-item="3-5"><div class="lab-step">Record any observations of spore or asci formation you observed in the table.
</div></li><li data-sub-note-item="3-6"><div class="lab-step">NOTE: Fungus from the Basidiomycota phylum exhibit clearly observable gills under the pileus.
</div></li><li data-sub-note-item="3-7"><div class="lab-step">Record any fungal species that demonstrated gills under the pileus.
</div></li></ul></li></ol>

Microbial Colony and Fungal Diversity - Procedure

Diversité microbienne et fongique

Examining Microbial Colony Structures
ExpandTo begin, collect your allocated culture plates and then remove the Parafilm and lid from one of them.
Place ...

Measuring Biodiversity

<ol class="note-items"><li data-note-item="1" data-parent-collapse="">Quadrats and Transects
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="1-1"><div class="lab-step">In this activity, you will be using quadrats along transect lines to take biodiversity measurements of the plant species in three distinct habitats near your classroom. Begin by splitting into groups. Four works best.
</div></li><li data-sub-note-item="1-2"><div class="lab-step">Select one person in your group to be the data recorder. The other three will be the data collectors.
</div></li><li data-sub-note-item="1-3"><div class="lab-step">Next, take one quadrat, or hula hoop, per group and place it on one side of one transect, or rope, next to a knot to allow identification of the plant species encircled by your quadrat. HYPOTHESES: For this experiment, the alternative hypothesis is that the alpha diversity will be smaller than gamma, meaning that there will be differences in the species that are present in each different habitat. The null hypothesis for this activity is that the alpha and gamma will be equal, meaning that there will be no species diversity difference between the communities sampled.
</div></li><li data-sub-note-item="1-4"><div class="lab-step">Each data collector must survey and identify the different plant species or any morphologically distinct varieties within your group&#39;s quadrat, giving the name of each plant type that you identify to the data recorder. It may seem like there are only a couple of species present at first, but look closer. It may take several minutes to find them all. 
</div></li><li data-sub-note-item="1-5"><div class="lab-step">In addition to recording the species name, the data recorder must also write a short description in the table, so that each species can be identified again in subsequent quadrats. <a href="https://www.jove.com/CDNSource/lm/labs/25/Table_1_Measuring_biodiversity.xlsx" style="display:block;margin:20px;" target="__blank">Click Here to download Table 1</a>
</div></li><li data-sub-note-item="1-6"><div class="lab-step">Once all of the species within a quadrat have been identified, pick up your hoop and move on to the next knot along the same transect.
</div></li><li data-sub-note-item="1-7"><div class="lab-step">Continue surveying and moving to the next knot until you have completed the entire rope transect.
</div></li><li data-sub-note-item="1-8"><div class="lab-step">Once you have completed the rope, move to a transect in a different habitat, and begin identifying the different species within each quadrat along the new transect, until each group has identified plants along three lengths of rope, one in each habitat, for a total of 15 quadrats surveyed.
</div></li><li data-sub-note-item="1-9"><div class="lab-step">When all of the species data have been collected, carry the transects and quadrats back to the classroom.
</div></li></ul></li><li data-note-item="2" data-parent-collapse="">Species-Accumulation Curves and Richness/Evenness 
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="2-1"><div class="lab-step">In the next activity, you will be calculating and comparing the species richness and evenness in two distinct populations, represented here by two opaque bags containing beads of various colors. For this exercise, start by taking one paper bag of beads per group.
</div></li><li data-sub-note-item="2-2"><div class="lab-step">Have one person reach into the bag and randomly pull out three beads without looking.
</div></li><li data-sub-note-item="2-3"><div class="lab-step">Write down the bead colors, as well as the total number of colors pulled from the bag in the table. <a href="https://www.jove.com/CDNSource/lm/labs/25/Table_2_Measuring_biodiversity.xlsx" style="display:block;margin:20px;" target="__blank">Click Here to download Table 2</a>HYPOTHESES: In this activity, the alternative hypothesis states that species evenness in the two communities will be different, while the richness will be the same. The null hypothesis might be that species richness and evenness will be the same in both communities.
</div></li><li data-sub-note-item="2-4"><div class="lab-step">Place the beads back in the bag after their colors are recorded.
</div></li><li data-sub-note-item="2-5"><div class="lab-step">Then, shake the bag and have the next person in the group draw another set of three beads.
</div></li><li data-sub-note-item="2-6"><div class="lab-step">Record the colors and numbers of beads that they pulled in the table.
</div></li><li data-sub-note-item="2-7"><div class="lab-step">Record the colors in the second row and the cumulative number of colors drawn in the last column.
</div></li><li data-sub-note-item="2-8"><div class="lab-step">Continue to take turns drawing three beads from the bag until 20 samples have been drawn.
</div></li><li data-sub-note-item="2-9"><div class="lab-step">Next, switch bags with a group with a bag from the other community, and repeat the exercise of drawing 20 samples, recording the color data in the appropriate community column of the table.
</div></li><li data-sub-note-item="2-10"><div class="lab-step">When all of the data have been recorded, return the beads to the bag and return the bags to your instructor.
</div></li></ul></li><li data-note-item="3" data-parent-collapse="">Results
<button class="expand">Expand</button><ul class="lab-items"><li data-sub-note-item="3-1"><div class="lab-step">To calculate the alpha diversity of the transect and quadrat data collected by your group, use the data your data recorder entered for each species and enter it into your diversity table. <a href="https://www.jove.com/CDNSource/lm/labs/25/Table_3_Measuring_biodiversity.xlsx" style="display:block;margin:20px;" target="__blank">Click Here to download Table 3</a>
</div></li><li data-sub-note-item="3-2"><div class="lab-step">Then, fill out the alpha diversity for each habitat into the appropriate column in the table.
</div></li><li data-sub-note-item="3-3"><div class="lab-step">Use the species data from your quadrat and transect table and enter the beta diversity data into the appropriate data cells within the diversity table. NOTE: The beta diversity is the number of species that are unique between two habitats. In this video, there are three species in common between the two sites, but a total of six unique species, giving a beta diversity of six between site A and B.
</div></li><li data-sub-note-item="3-4"><div class="lab-step">To calculate the gamma diversity for your activity, use the data from your quadrat and transect table and enter the gamma diversity data into the appropriate data cell. NOTE: The gamma diversity is the number of species in all of the habitats within a single study. It is not the sum of all of the alpha diversities, because species that are common between habitats should be counted only once.
</div></li><li data-sub-note-item="3-5"><div class="lab-step">To construct species accumulation curves for both of the bead sampling communities, use your bead color selection data to plot the species by sampling effort. That is the number of total colors by sample in the graph for each bead bag community.
</div></li><li data-sub-note-item="3-6"><div class="lab-step">Then, estimate the asymptote of the plotted data by appearance. Predict the number of species you would expect to find in each community. Note any differences in appearance between the two curves. If it was easier to estimate the number of species in one of the communities, make a hypothesis to explain this observation.
</div></li><li data-sub-note-item="3-7"><div class="lab-step">To construct rank abundance curves for both of the bead sampling communities, use the color bead data to fill in the table for both community A and community B, listing the colors that were identified during the sampling in the color column, and adding the total number of beads of each color that was sampled in the abundance column. <a href="https://www.jove.com/CDNSource/lm/labs/25/Table_4_Measuring_biodiversity.xlsx" style="display:block;margin:20px;" target="__blank">Click Here to download Table 4</a>
</div></li><li data-sub-note-item="3-8"><div class="lab-step">Now, assign a rank to each color in the rank column, designating the color of the highest abundance the highest rank, rank one, and the color with the lowest abundance the lowest rank, rank 10. If there are multiple colors with the same number, just assign them consecutive ranks.
</div></li><li data-sub-note-item="3-9"><div class="lab-step">Plot individual rank abundance curves for the number of individuals by species ranked for the most to least common in both community A and community B. Compare the steepness of the two rank curves. Compare the richness and evenness between the two communities. Identify the community that you consider more biodiverse. 
</div></li></ul></li></ol>

Mesurer la biodiversité

Quadrats and Transects
ExpandIn this activity, you will be using quadrats along transect lines to take biodiversity measurements of the plant species in ...

Découvrir l’anatomie oreille moyenne par chirurgie endoscopique oreille Transcanal : un manuel de Dissection

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