The Aguirre Lab is supported by the National Heart, Lung, and Blood Institute of the National Institutes of Health under award number K01HL135464 and by the American Heart Association under award number 19IPLOI34660342.

All animals used in the experiments referenced in this paper were treated using the animal care guidelines of the Michigan State University Institutional Animal Care and Use Committee (IACUC).
1. Timed mating of C57BL6/J mice for embryo production
<ol>
	<li>Once mice have reached breeding age (6-8 weeks), put them together in harem breeding format (i.e., two females per one male). Set them up for breeding sometime in the afternoon or evening. 
	NOTE: Mice often breed within 1 h after li...

<ol>
	<li>Kathiresan, S., Srivastava, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetics+of+human+cardiovascular+disease.">Genetics of human cardiovascular disease.</a> Cell. 148 (6), 1242-1257 (2012).</li><li>Sun, R., Liu, M., Lu, L., Zheng, Y., Zhang, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Congenital+Heart+Disease:+Causes,+Diagnosis,+Symptoms,+and+Treatments.">Congenital Heart Disease: Causes, Diagnosis, Symptoms, and Treatments.</a> Cell Biochemistry and Biophysics. 72 (3), 857-860 (2015).</li><li>Hoffman, J. I. E., Kaplan, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+incidence+of+congenital+heart+disease.">The incidence of congenital heart disease.</a> Journal of the American College of Cardiology. 39 (12), 1890-1900 (2002).</li><li>Fahed, A. C., Gelb, B. D., Seidman, J. G., Seidman, C. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetics+of+congenital+heart+disease:+The+glass+half+empty.">Genetics of congenital heart disease: The glass half empty.</a> Circulation Research. 112 (4), 707-720 (2013).</li><li>Pelech, A. N., Broeckel, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Toward+the+etiologies+of+congenital+heart+diseases.">Toward the etiologies of congenital heart diseases.</a> Clinics in Perinatology. 32 (4), 825-844 (2005).</li><li>Zaidi, S., Brueckner, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetics+and+Genomics+of+Congenital+Heart+Disease.">Genetics and Genomics of Congenital Heart Disease.</a> Circulation Research. 120 (6), 923-940 (2017).</li><li>Kenny, L. A., 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=Transplantation+in+the+single+ventricle+population.">Transplantation in the single ventricle population.</a> Annals of Cardiothoracic Surgery. 7 (1), 152-159 (2018).</li><li>Navaratnam, D., 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=Exercise-Induced+Systemic+Venous+Hypertension+in+the+Fontan+Circulation.">Exercise-Induced Systemic Venous Hypertension in the Fontan Circulation.</a> The American Journal of Cardiology. 117 (10), 1667-1671 (2016).</li><li>De Leval, M. R., Deanfield, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Four+decades+of+Fontan+palliation.">Four decades of Fontan palliation.</a> Nature Reviews Cardiology. 7 (9), 520-527 (2010).</li><li>Buckberg, G. D., Hoffman, J. I. E., Coghlan, H. C., Nanda, N. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ventricular+structure-function+relations+in+health+and+disease:+part+II.+Clinical+considerations.">Ventricular structure-function relations in health and disease: part II. Clinical considerations.</a> European Journal of Cardio-Thoracic Surgery : Official Journal of the European Association for Cardio-thoracic Surgery. 47 (5), 778-787 (2015).</li><li>Jenkins, K. J., 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=Noninherited+risk+factors+and+congenital+cardiovascular+defects:+Current+knowledge+-+A+scientific+statement+from+the+American+Heart+Association+Council+on+Cardiovascular+Disease+in+the+Young.">Noninherited risk factors and congenital cardiovascular defects: Current knowledge - A scientific statement from the American Heart Association Council on Cardiovascular Disease in the Young.</a> Circulation. 115 (23), 2995-3014 (2007).</li><li>Botto, L. D., 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=Lower+rate+of+selected+congenital+heart+defects+with+better+maternal+diet+quality+:+a+population-based+study.">Lower rate of selected congenital heart defects with better maternal diet quality : a population-based study.</a> Archives of Disease in Childhood - Fetal and Neonatal Edition. 101 (1), F43-F49 (2016).</li><li>Knowles, R. 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=Ethnic+and+socioeconomic+variation+in+incidence+of+congenital+heart+defects.">Ethnic and socioeconomic variation in incidence of congenital heart defects.</a> Archives of Disease in Childhood. 102 (6), 496-502 (2017).</li><li>Feng, Y., 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=Maternal+Folic+Acid+Supplementation+and+the+Risk+of+Congenital+Heart+Defects+in+Offspring+:+A+Meta-Analysis+of+Epidemiological+Observational+Studies.">Maternal Folic Acid Supplementation and the Risk of Congenital Heart Defects in Offspring : A Meta-Analysis of Epidemiological Observational Studies.</a> Scientific Reports. 17 (5), 8506 (2015).</li><li>Rhinn, M., Dolle, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Retinoic+acid+signalling+during+development.">Retinoic acid signalling during development.</a> Development. 139 (5), 843-858 (2012).</li><li>Liu, Y., 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=Circulating+retinoic+acid+levels+and+the+development+of+metabolic+syndrome.">Circulating retinoic acid levels and the development of metabolic syndrome.</a> The Journal of Clinical Endocrinology &amp; Metabolism. 101 (February), 2015 (2016).</li><li>Kurian, 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=Identification+of+novel+long+noncoding+RNAs+underlying+vertebrate+cardiovascular+development.">Identification of novel long noncoding RNAs underlying vertebrate cardiovascular development.</a> Circulation. 131 (14), 1278-1290 (2015).</li><li>Aguirre, A., Sancho-Martinez, I., Izpisua Belmonte, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reprogramming+toward+heart+regeneration:+Stem+cells+and+beyond.">Reprogramming toward heart regeneration: Stem cells and beyond.</a> Cell Stem Cell. 12 (3), 275-284 (2013).</li><li>Srivastava, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Making+or+breaking+the+heart:+from+lineage+determination+to+morphogenesis.">Making or breaking the heart: from lineage determination to morphogenesis.</a> Cell. 126 (6), 1037-1048 (2006).</li><li>Heyne, G. W., 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=A+simple+and+reliable+method+for+early+pregnancy+detection+in+inbred+mice.">A simple and reliable method for early pregnancy detection in inbred mice.</a> Journal of the American Association for Laboratory Animal Science. 54 (4), 368-371 (2015).</li><li>. Stage Definition Available from: <a target="_blank" href="https://www.emouseatlas.org/emap/ema/theiler_stages/StageDefinition/stagedefinition.html">https://www.emouseatlas.org/emap/ema/theiler_stages/StageDefinition/stagedefinition.html</a> (1998)</li><li>Part 4-Measure Areas using Thresholding. Science Education Resource Center Available from: <a target="_blank" href="https://serc.carleton.edu/eet/measure_sat2/part_4.html">https://serc.carleton.edu/eet/measure_sat2/part_4.html</a> (2017)</li><li>. Examples of Image Analysis Using ImageJ Available from: <a target="_blank" href="https://imagej.nih.gov/ij/docs/pdfs/examples.pdf">https://imagej.nih.gov/ij/docs/pdfs/examples.pdf</a> (2007)</li><li>MacIver, D. H., Adeniran, I., Zhang, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Left+ventricular+ejection+fraction+is+determined+by+both+global+myocardial+strain+and+wall+thickness.">Left ventricular ejection fraction is determined by both global myocardial strain and wall thickness.</a> IJC Heart and Vasculature. 1 (7), 113-118 (2015).</li><li>Towbin, J. A., Ballweg, J., Johnson, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Left+Ventricular+Noncompaction+Cardiomyopathy.">Left Ventricular Noncompaction Cardiomyopathy.</a> Heart Failure in the Child and Young Adult: From Bench to Bedside. , 269-290 (2018).</li><li>Choi, Y., Kim, S. M., Lee, S. C., Chang, S. A., Jang, S. Y., Choe, Y. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantification+of+left+ventricular+trabeculae+using+cardiovascular+magnetic+resonance+for+the+diagnosis+of+left+ventricular+non-compaction:+evaluation+of+trabecular+volume+and+refined+semi-quantitative+criteria.">Quantification of left ventricular trabeculae using cardiovascular magnetic resonance for the diagnosis of left ventricular non-compaction: evaluation of trabecular volume and refined semi-quantitative criteria.</a> Journal of Cardiovascular Magnetic Resonance. 18 (1), 24 (2016).</li></ol>

This protocol explores the techniques involved in the analysis of cardiac development in embryonic hearts. Some limitations of this method are the required physical dexterity for the preparatory techniques, which may require practice, and skill with microscope imaging. If the slices obtained at the cryostat are messy, the hematoxylin and eosin staining will not be clear, or if the images taken at the microscope have poor lighting, then the method used with ImageJ will not work. A limitation of the threshold feature of Im...

CHDs are the most common type of birth defect in humans and are the leading cause of birth defect-related deaths1,2,3,4,5,6. Although about 90% of newborn children survive CHD, it is frequently associated with significant morbidity and medical interventions over the years, imposing a heavy burden on the patients&#39; lives and the healthcare system7,8,9,10. Outside of purely genetic factors, the causes of CHD are poorly understood4. Unidentified causes account for ~56-66% of all CHD cases according to the American Heart Association and other sources2,3,4,11. Well-known factors include genetic mutations, CNVs, de novo single nucleotide variants, and aneuploidy. It is suspected that environmental and dietary factors are also important sources contributing to CHD, as suggested by epidemiological studies linking maternal lifestyle2,12, economic deprivation, and race13, and by research into dietary factors such as folic acid11,14 and the bioactive lipid retinoic acid15,16. Investigating the mechanisms and causes of CHD and other cardiovascular defects is important to develop preventive strategies and novel therapeutic options1,4,17,18,19.
The developing mouse is a cornerstone model for studying CHD in mammals. However, some of the methods and analyses employed, such as dissections preserving heart morphology, analysis of developmental stages, and identification of CHD-associated defects, can be daunting for scientists that are new to the analysis of murine hearts. The goal of the methods described in this protocol is to offer qualitative and quantitative guidelines for these processes. Thus, in this protocol we explain how to perform timed matings to produce embryos of the desired gestational stage, dissect pregnant females for intact heart recovery (including associated tissues such as the outflow tract), heart fixation and preparation for cryostat sectioning, basic histology methods, quantitative analyses of common heart defects, and qualitative analysis of heart muscle compaction, a common precursor phenotype to some types of CHD.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>15 mL Conical Tube(s)</td>
			<td>Fisher Scientific</td>
			<td># 1495970C</td>
			<td></td>
		</tr>
		<tr>
			<td>C57BL/6J Mice</td>
			<td>Jackson Labs</td>
			<td>C57BL/6J - stock 000664</td>
			<td></td>
		</tr>
		<tr>
			<td>Coplin Staining Jars (x6)</td>
			<td>VWR Scientific</td>
			<td># 25457-006</td>
			<td></td>
		</tr>
		<tr>
			<td>Coverslips 24X50MM #1.5</td>
			<td>VWR Scientific</td>
			<td># 48393-241</td>
			<td></td>
		</tr>
		<tr>
			<td>Cryostat - Leica CM3050S</td>
			<td>Leica</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>Dissecting Dish(s)</td>
			<td>Fisher Scientific</td>
			<td># 50930381</td>
			<td></td>
		</tr>
		<tr>
			<td>Dumont #5 - Fine Forceps (x2)</td>
			<td>Fine Science Tools</td>
			<td># 11254-20</td>
			<td></td>
		</tr>
		<tr>
			<td>Eosin Y Solution</td>
			<td>Millipore Sigma</td>
			<td># HT110116-500ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethyl Alcohol (Pure, 200 proof)</td>
			<td>Fisher Scientific</td>
			<td># BP2818-500</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethylenediaminetetraacetic acid (EDTA)</td>
			<td>Millipore Sigma</td>
			<td># E9884-100G</td>
			<td></td>
		</tr>
		<tr>
			<td>Eukitt</td>
			<td>Millipore Sigma</td>
			<td># 03989-100ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Fine Scissors</td>
			<td>Fine Science Tools</td>
			<td># 14060-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorescent Stereo Microscope Leica M165 FC</td>
			<td>Leica</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>Glycine</td>
			<td>Millipore Sigma</td>
			<td># 410225-250G</td>
			<td></td>
		</tr>
		<tr>
			<td>Graefe Forceps</td>
			<td>Fine Science Tools</td>
			<td># 11052-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Graphpad Prism 8 Software</td>
			<td>Graphpad</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>ImageJ Software</td>
			<td>ImageJ</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Kimwipes</td>
			<td>Fisher Scientific</td>
			<td># 06666A</td>
			<td></td>
		</tr>
		<tr>
			<td>Mayer&#39;s hematoxylin solution</td>
			<td>Millipore Sigma</td>
			<td># MHS16-500ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Micropipette tip(s) - p200</td>
			<td>Fisher Scientific</td>
			<td># 02707448</td>
			<td></td>
		</tr>
		<tr>
			<td>Microsoft Excel Software</td>
			<td>Microsoft</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>OCT Compound</td>
			<td>VWR Scientific</td>
			<td># 102094-106</td>
			<td></td>
		</tr>
		<tr>
			<td>Olympus CkX53 Microscope</td>
			<td>Olympus</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Paint Brushes (at least 2)</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Paraformaldehyde</td>
			<td>VWR Scientific</td>
			<td># 0215014601</td>
			<td>Make into 4% solution (dissolved in PBS)</td>
		</tr>
		<tr>
			<td>Pasteur pipette(s)</td>
			<td>Fisher Scientific</td>
			<td># 13-711-7M</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin-Streptomycin</td>
			<td>ThermoFisher Scientific</td>
			<td># 15140122</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate Buffered Saline (PBS)</td>
			<td>ThermoFisher Scientific</td>
			<td># 70011044</td>
			<td>Dilute from 10x to 1x before using</td>
		</tr>
		<tr>
			<td>Scale</td>
			<td>Mettler Toledo</td>
			<td># MS1602TS</td>
			<td></td>
		</tr>
		<tr>
			<td>Scale</td>
			<td>Mettler Toledo</td>
			<td># MS105</td>
			<td></td>
		</tr>
		<tr>
			<td>Scalpel Handle #3</td>
			<td>VWR Scientific</td>
			<td># 10161-918</td>
			<td></td>
		</tr>
		<tr>
			<td>Scalpel Blades</td>
			<td>VWR Scientific</td>
			<td># 21909-612</td>
			<td></td>
		</tr>
		<tr>
			<td>Square Mold</td>
			<td>VWR Scientific</td>
			<td># 100500-224</td>
			<td>For OCT molds</td>
		</tr>
		<tr>
			<td>Sucrose</td>
			<td>Millipore Sigma</td>
			<td># S9378-500G</td>
			<td></td>
		</tr>
		<tr>
			<td>Superfrost Plus Slides</td>
			<td>Fisher Scientific</td>
			<td># 1255015</td>
			<td></td>
		</tr>
		<tr>
			<td>Surgical Scissors</td>
			<td>Fine Science Tools</td>
			<td># 14002-14</td>
			<td></td>
		</tr>
		<tr>
			<td>Tissue-Tek Accu-Edge Disposable Microtome Blades</td>
			<td>VWR Scientific</td>
			<td># 25608-964</td>
			<td></td>
		</tr>
		<tr>
			<td>Travel Scale</td>
			<td>Acculab</td>
			<td>VIC 5101</td>
			<td></td>
		</tr>
		<tr>
			<td>Xylene</td>
			<td>Millipore Sigma</td>
			<td>214736-1L</td>
			<td></td>
		</tr>
	</tbody>
</table>

analysis of congenital heart defects in mouse embryos using qualitative and quantitative histological methods

Congenital heart defects (CHD) are the most common type of birth defect in humans, affecting up to 1% of all live births. However, the underlying causes for CHD are still poorly understood. The developing mouse constitutes a valuable model for the study of CHD, because cardiac developmental programs between mice and humans are highly conserved. The protocol describes in detail how to produce mouse embryos of the desired gestational stage, methods to isolate and preserve the heart for downstream processing, quantitative methods to identify common types of CHD by histology (e.g., ventricular septal defects, atrial septal defects, patent ductus arteriosus), and quantitative histomorphometry methods to measure common muscular compaction phenotypes. These methods articulate all the steps involved in sample preparation, collection, and analysis, allowing scientists to correctly and reproducibly measure CHD.

The muscle compaction index was compared between hearts developing under two different environments, a control and an experimental group. These protocols were used to analyze the compaction of muscle tissue quantitatively, which permitted statistical analysis. Muscle compaction was shown to be significantly reduced in the experimental hearts relative to the embryos that developed in nonexperimental conditions.
Embryos were disca...

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Analysis of Congenital Heart Defects in Mouse Embryos Using Qualitative and Quantitative Histological Methods

In this protocol, we describe procedures to qualitatively and quantitatively analyze developmental phenotypes in mice associated with congenital heart defects.

Congenital heart defects (CHD) are the most common type of birth defect in humans, affecting up to 1% of all live births. However, the underlying causes ...

This protocol standardizes new tissue analysis techniques so that they can be more widely used by other groups who also study congenital heart defects. As both qualitative and quantitative analysis techniques have their pros and cons, this methodology uses both to address the widest range of experimental questions. These techniques can have a positive impact on cardiology diagnostic methods.For example, pathologists could apply our microscopic cardiac tissue analysis techniques towards diagnosing human heart disease from biopsy samples. This protocol can be used for developmental cardiology or general cardiology research. However, these methods also provide various useful techniques that can be applied towards any tissue analysis.To collect embryonic day 15 to 15.5 hearts, secure the limbs of a pregnant dam and starting around the urethra up to the sternum, carefully make an I-shaped incision along the torso. Using forceps in a scooping motion, gently lift the uterus out of the abdominal cavity grasping the superficial tissues of the uterus as necessary with fine forceps to aid in the extraction. Use scissors to release the uterus from the abdomen.After soaking the uterus in ice-cold PBS, pin the organ into a dissection dish. Using scissors, cut the uterus into individual sections each containing a separate embryo. Using two pairs of fine forceps, gently peel the embryos out of the uterine tissue and place them in to a new Petri dish containing four degrees Celsius PBS-EDTA.To collect the hearts, place the dish under a dissecting microscope and use two pairs of fine forceps to position the embryo into the supine position. After stabilizing access to the chest, use the sharp point of a second pair of fine forceps to make an incision along the sternum of the embryo extending between the clavicles to the navel. Making very fine and superficial incisions while gradually working toward the inside of the chest cavity, open the abdomen of the embryo.When the heart just becomes visible, use a pair of forceps to squeeze the torso slightly coddled to the rib cage to peel the ribs open. Using the sides of one pair of forceps, gently grab the pulmonary blood vessels without separating the tissue and pull the heart out of the cavity. Clean the heart in fresh PBS-EDTA for one to two minutes before fixing the tissue in 4%Paraformaldehyde for 45 to 60 minutes.Then, wash the heart three times for 5 to 10 minutes per wash in PBS supplemented with glycine. Before storing the hearts in PBS at four degrees Celsius. To prepare the heart for cryosectioning, place the samples into a tube of 30%sucrose and PBS at four degrees Celsius for 24 to 40 hours.When the hearts have sunk to the bottom of the tube, use a Pasteur Pipette with a modified tip to carefully transfer each heart unto a piece of lint free wipe. After a brief air-drying, place each sample into individual optimal cutting temperature molds in the desired orientations for sectioning. Submerge the tissues in optimal cutting temperature medium without bubbles.Then, store the molds at 20 degrees Celsius for up to a few days before freezing the tissues at 80 degrees Celsius for at least 24 hours before cryosectioning. To obtain cryostat sections of the samples, use fresh optimal temperature cutting medium to attach the tissue block of interest to the chuck of the cryostat and allow the medium to freeze until it is opaque white. Insert a new blade and adjust the distance between the tissue block and the blade to allow sections to be obtained.Trim the block in 10 micrometer slices until the point of interest is reached. When the tissue can be observed, use a small flat paintbrush to gently pull the slice against the stand in a continuous cutting motion. Once the tissue has been completely cut through, use the detail brush to pat the slice down flat against the stage.Hold the section in place for approximately 20 to 30 seconds before removing the detailed brush and finishing the slice. Use both paintbrushes to gently flatten the slice against the stage preventing any rolling and hold the tissue section against the stage. After 20 to 30 seconds, flip the section and flatten it against the stage again before placing an electrostatically charged slide close enough for the slice to be attracted and adhere to the slide without having to touch the slide to the stage.To evaluate the heart tissue sections for the presence of common heart defects, using a microscope equipped with a camera, obtain images at 5 to 10X and 40X magnifications. For cardiac muscle compaction analysis, open a tissue of interest in an appropriate image analysis software program and set the image to 8-bit. To set the threshold of the image, click Image, Adjust, and Threshold and move the top bar to adjust the threshold until only the pixels for the background are selected.Next, use the polygon selections tool to draw a region of interest around the tissue then click Analyze, Set Measurements, Area, and Limit to threshold. Click Analyze and Measure to measure the area of the highlighted pixels to obtain the value of the area of the negative space. To measure the area of the entire region of interest, click Analyze, Set Measurements, and deselect Limit to threshold.Then, select Analyze and Measure to measure the entire area of the selected region of interest. To calculate the Area of muscle tissue, subtract the Area of Negative Space from the Area of the Region of Interest. Then divide the Area of muscle tissue by the Area of the Region of Interest to calculate the muscle compaction and X.The staining of tissue slices from harvested embryonic hearts, provides enough contrast to make out the tissue edges, but is not so dark as to make the cell features indistinguishable.In this representative analysis, the muscle compaction was observed to be significantly reduced in the experimental hearts relative to the embryos that developed under non-experimental conditions. These samples are valuable and require a long time to create. During necropsies and the cryostat sectioning specifically, make sure to be intentional about every action you perform.Preserving the tissues in Paraformaldehyde maintains the antigen activity permitting the samples to be used for tests like Aminofluorescein staining which help identify pathological causes found during the morphology assessment. In our lab, we obtained quantitative representation of experimental treatments which can help us to identify the degree to which different treatments affect our samples. Paraformaldehyde can fix any tissue that it touches.Take care to always wear gloves to minimize exposed skin and to work in a film hood whenever working with this chemical.

analysis-congenital-heart-defects-mouse-embryos-using-qualitative

Research

JoVE Journal

Developmental Biology

6.6K visualizações.  Michigan State University. Este protocolo padroniza novas técnicas de análise de tecidos para que possam ser mais amplamente utilizadas por outros grupos que também estudam defeitos cardíacos congênitos. Como tanto as técnicas de análise qualitativa quanto quantitativa têm seus prós e contras, essa metodologia utiliza tanto para abordar a mais ampla gama de questões experimentais. Essas técnicas podem ter um impacto positivo nos métodos de diagnóstico de cardiologia.Por exemplo, os patologistas pode...