The authors would like to thank Gregory Haller (Mount Saint Vincent University) for his preliminary work in the development of the protocol. The authors would also like to thank Nicholas Jones (Mount Saint Vincent University) for his technical expertise and assistance with the filming and production of the audio/visual portion of the manuscript. Daniel Andrews was supported by funding from MSVU and the Natural Sciences and Engineering Research Council of Canada (NSERC) via an Undergraduate Student Research Award. Tamara A. Franz-Odendaal is supported by an NSERC Discovery Grant.

NOTE: For embryo stages, utilize the Hamburger and Hamilton12 (HH) staging table.
1. Embryo Incubation
<ol>
	<li>Incubate fertilized chicken eggs in a sterile, temperature-controlled incubator at 37 &#176;C &#177; 1 &#176;C and ~40% humidity.</li>
	<li>Turn the eggs 1x per day and allow them to incubate to HH34 (8 days post-fertilization).</li>
</ol>
2. Preparation and Sterilization of the Materials
<ol>
	<li>For 12 embryos, autoclave 2 L of distilled water, 1 L of 0.85% chick saline, 12 glass pipettes, 1 box of paper tissue, 24 2.5 cm x 2.5 cm squares of semi-porous filter paper, and 24 2.5 cm x 2.5 cm squares of steel wire mesh with the edges curved downwards. To sterilize the materials, autoclave them at 121 &#176;C for at least 15 min. 
	NOTE: The autoclaving of the materials can be done in advance.</li>
	<li>Sterilize the incubator with 70% ethanol by wiping the sides, shelves, and door. Place 2 plastic containers containing autoclaved distilled water inside the incubator to maintain humidity. Prewarm the culture incubator to 37 &#176;C &#177; 1 &#176;C and ~40% humidity. Ensure the incubator is completely dark; if the door is transparent, cover it with tinfoil.</li>
	<li>Prewarm 100 mL of nutrient medium and 1 mL of penicillin by placing them in the culture incubator.</li>
	<li>Cover the workspace with a paper towel and sterilize the bench by spraying it with 70% ethanol. Sterilize 2 pairs of forceps, dissection scissors, a razor blade, and a plastic spoon with 70% ethanol in a similar manner.</li>
	<li>Place 12 sterile 100 mm Petri dishes and 24 sterile 35 mm Petri dishes on the bench for use. Ensure the dishes remain in a sterile bag until use.</li>
</ol>
3. Embryo Preparation
NOTE: From this point onwards, wear a protective dust face mask to avoid contaminating the cultures. A bacterial or fungal infection will ruin the culture and there is a risk of it spreading quickly to all cultures in the incubator.
<ol>
	<li>Crack open the egg and transfer the embryo to a 100 mm Petri dish containing 0.85% chick saline. Stage the embryo according to the anatomical features described in the Hamburger and Hamilton staging guidelines12 and confirm the embryo is at HH34.</li>
	<li>Cut the neck and then bisect the head of the embryo at the midline using a sterilized razor blade. Using sterile forceps, remove the brain. Leave the beak intact.</li>
</ol>
4. Culture Setup
<ol>
	<li>Place 2 of the 35 mm Petri dishes inside one 100 mm Petri dish.</li>
	<li>Place a steel wire mesh inside each 35 mm Petri dish.</li>
	<li>Using forceps, transfer 1 of the bisected heads to a piece of 2.5 cm x 2.5 cm semi-porous filter paper with the eye facing up. Ensure the tissue is secure and does not slip off by tilting it slightly.</li>
	<li>Using forceps, carefully place the eye tissue and the filter paper on top of the steel wire mesh in 1 of the 35 mm Petri dishes, creating a raised stage with the eye tissue on top.</li>
	<li>Repeat steps 4.3 and 4.4 with the other half head.</li>
	<li>Using a sterile glass pipette, carefully add nutrient medium directly into each 35 mm Petri dish until it reaches the level of the filter paper. Do not submerge the half head in the nutrient medium.</li>
	<li>Add 50 &#181;L of 10,000 U/mL penicillin-streptomycin to the nutrient medium in each Petri dish.</li>
	<li>Fold a piece of tissue paper into a small square and place it inside the 100 mm Petri dish. Moisten it with autoclaved distilled water.</li>
	<li>Place the culture dish into the sterile, dark incubator at 37 &#176;C &#177; 1 &#176;C and ~40% humidity for up to 4 days.</li>
	<li>Repeat steps 3 and 4 for each embryo. 
	NOTE: The number of embryos needed will depend on the specific experiment; here, we describe the protocol for 12 embryos.</li>
</ol>
5. Culture Maintenance
<ol>
	<li>Once per day, top up the plastic containers in the incubator with fresh, autoclaved distilled water.</li>
	<li>Daily check all cultures for bacterial or fungal infections. Cultures that have disintegrated or in which the medium has changed color are infected. Discard all cultures that are infected.</li>
</ol>
6. Fixation
<ol>
	<li>Following culturing, remove all dishes from the incubator.</li>
	<li>Using a pair of forceps, gently remove the eye from the filter paper, taking care not to tear the tissue.</li>
	<li>Fix the eye tissue in 4% paraformaldehyde in 1x phosphate-buffered saline overnight at 4 &#176;C or in 10% neutral-buffered formalin overnight at room temperature.</li>
	<li>Store the tissue at 4 &#176;C in 1x phosphate-buffered saline.</li>
</ol>

<ol>
	<li>Franz-Odendaal, T. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Towards+understanding+the+development+of+scleral+ossicles+in+the+chicken,+Gallus+gallus.">Towards understanding the development of scleral ossicles in the chicken, Gallus gallus.</a> Developmental Dynamics. 237 (11), 3240-3251 (2008).</li><li>Scholey, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functions+of+motor+proteins+in+echinoderm+embryos:+an+argument+in+support+of+antibody+inhibition+experiments.">Functions of motor proteins in echinoderm embryos: an argument in support of antibody inhibition experiments.</a> Cell Motility and the Cytoskeleton. 39 (4), 257-260 (1998).</li><li>Horakova, 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=Effect+of+FGFR+inhibitors+on+chicken+limb+development.">Effect of FGFR inhibitors on chicken limb development.</a> Development, Growth &amp; Differentiation. 56 (8), 555-572 (2014).</li><li>Gerlach, G. F., Morales, E. E., Wingert, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microbead+Implantation+in+the+Zebrafish+Embryo.">Microbead Implantation in the Zebrafish Embryo.</a> Journal of Visualized Experiments. (101), e52943 (2015).</li><li>Luz-Madrigal, A., Grajales-Esquivel, E., Del Rio-Tsonis, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electroporation+of+Embryonic+Chick+Eyes.">Electroporation of Embryonic Chick Eyes.</a> Bio-protocol. 5 (12), e1498 (2015).</li><li>Roach, H. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Long-term+organ+culture+of+embryonic+chick+femora:+a+system+for+investigating+bone+and+cartilage+formation+at+an+intermediate+level+of+organization.">Long-term organ culture of embryonic chick femora: a system for investigating bone and cartilage formation at an intermediate level of organization.</a> Journal of Bone and Mineral Research. 5 (1), 85-100 (1990).</li><li>Jung, H. S., 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=Local+inhibitory+action+of+BMPs+and+their+relationships+with+activators+in+feather+formation:+implications+for+periodic+patterning.">Local inhibitory action of BMPs and their relationships with activators in feather formation: implications for periodic patterning.</a> Developmental Biology. 196 (1), 11-23 (1998).</li><li>McKinnell, I. W., Turmaine, M., Patel, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sonic+Hedgehog+functions+by+localizing+the+region+of+proliferation+in+early+developing+feather+buds.">Sonic Hedgehog functions by localizing the region of proliferation in early developing feather buds.</a> Developmental Biology. 272 (1), 76-88 (2004).</li><li>Smith, E. L., Kanczler, J. M., Oreffo, R. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+take+on+an+old+story:+chick+limb+organ+culture+for+skeletal+niche+development+and+regenerative+medicine+evaluation.">A new take on an old story: chick limb organ culture for skeletal niche development and regenerative medicine evaluation.</a> European Cells &amp; Materials. 26, 91-106 (2013).</li><li>Sato, T., 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=In+Vitro+Spermatogenesis+in+Explanted+Adult+Mouse+Testis+Tissues.">In Vitro Spermatogenesis in Explanted Adult Mouse Testis Tissues.</a> PLoS One. 10 (6), e0130171 (2015).</li><li>Ochoa-Villarreal, 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=Plant+cell+culture+strategies+for+the+production+of+natural+products.">Plant cell culture strategies for the production of natural products.</a> BMB Reports. 49 (3), 149-158 (2016).</li><li>Hamburger, V., Hamilton, H. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+series+of+normal+stages+in+the+development+of+the+chick+embryo.">A series of normal stages in the development of the chick embryo.</a> Journal of Morphology. 88 (1), 49-92 (1951).</li><li>Yu, 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+developmental+biology+of+feather+follicles.">The developmental biology of feather follicles.</a> The International Journal of Developmental Biology. 48, 181-191 (2004).</li><li>Jabalee, J., Hillier, S., Franz-Odendaal, T. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+investigation+of+cellular+dynamics+during+the+development+of+intramembranous+bones:+the+scleral+ossicles.">An investigation of cellular dynamics during the development of intramembranous bones: the scleral ossicles.</a> Journal of Anatomy. 223 (4), 311-320 (2013).</li><li>Trowell, O. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+culture+of+mature+organs+in+a+synthetic+medium.">The culture of mature organs in a synthetic medium.</a> Experimental Cell Research. 16 (1), 118-147 (1959).</li><li>Pinto, C. B., Hall, B. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Toward+an+understanding+of+the+epithelial+requirement+for+osteogenesis+in+scleral+mesenchyme+of+the+embryonic+chick.">Toward an understanding of the epithelial requirement for osteogenesis in scleral mesenchyme of the embryonic chick.</a> Journal of Experimental Zoology. 259 (1), 92-108 (1991).</li><li>Mbiene, J. P., MacCallum, D. K., Mistretta, C. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Organ+cultures+of+embryonic+rat+tongue+support+tongue+and+gustatory+papilla+morphogenesis+in+vitro+without+intact+sensory+ganglia.">Organ cultures of embryonic rat tongue support tongue and gustatory papilla morphogenesis in vitro without intact sensory ganglia.</a> Journal of Comparative Neurology. 377 (3), 324-340 (1997).</li><li>Cloney, K., Franz-Odendaal, T. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optimized+ex-ovo+culturing+of+chick+embryos+to+advanced+stages+of+development.">Optimized ex-ovo culturing of chick embryos to advanced stages of development.</a> Journal of Visualized Experiments. (95), e52129 (2015).</li><li>Korn, M. J., Cramer, K. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Windowing+chicken+eggs+for+developmental+studies.">Windowing chicken eggs for developmental studies.</a> Journal of Visualized Experiments. (8), e306 (2007).</li></ol>

The authors have nothing to disclose.

This protocol makes use of established tissue culturing techniques to achieve the growth of a chicken eye from embryonic day 8 (HH34) in vitro for 4 days. This grid-culturing method was originally described by Trowell15. We optimized a protocol from Pinto and Hall&#39;s 1991 study16 utilizing a semi-porous membrane with the grid to study inductive signals between separated tissue layers of the embryonic chicken eye15. Using this method, Roac...

The embryonic chicken (Gallus gallus) is an excellent model organism commonly used in the field of biology. Its incubation period is roughly 21 days and many eggs can be incubated simultaneously, making experimentation quick and efficient. Perhaps most importantly, the embryo is also easily manipulated, enabling the extensive study of key developmental processes and of the genes and proteins that drive these processes.
The embryonic chicken eye is a complex organ that develops via the interaction of a number of different tissues similar to many other body systems. This method enables the study of the development of these tissues, particularly at advanced stages of development. For example, the multi-layered retina may be of particular interest to those studying the development of the nervous system. Alternative methods that enable the study of other eye tissues such as the cornea, the vitreal body, the lens, the sclera, and the eyelids are of benefit to researchers. The chicken embryonic eye also contains a series of flat bones, the scleral ossicles, which can be used as a model for the study of intramembranous bone induction and ossification in vertebrates1.
Currently, there are a number of methods used to study embryonic development. Microinjections of inhibitory antibodies or other inhibitory molecules2,3, surgically implanted microbeads soaked in inhibitor4, and electroporation5 are all methods that can be used to downregulate genes or proteins of interest in an embryo. Similar methods are used to upregulate proteins. These methods are not without their limitations. For example, when using chemicals to alter the embryonic development, the lethal effects on the embryo must be evaluated, and this limits the use of the aforementioned methods to localized sites of application at doses low enough to ensure the survivability of the embryo.
In vitro tissue&#160;culturing has been used in a wide range of organisms to study development and can be used to bypass some of the aforementioned limitations. For example, the femora6, feather buds7,8, and limbs9 of the chicken have all been studied using tissue culturing methods, as have the testes of the mouse10 and the roots and stems of plants11. These methods grant scientists a high degree of control over the tissue development, such as the ability to fluctuate the temperature and alter the nutrient availability. The isolation of the tissue from the whole embryo also makes it far less susceptible to the lethal effects of chemicals, thus enabling manipulation studies on a global scale at higher concentrations. Another notable advantage of in vitro culturing is the preservation of the tissue&#39;s cellular environment; the arrangement of tissues remains relatively unchanged, making it possible to study the interactions between different tissue types9. Thus, in vitro culturing opens doors to additional experimental approaches not available in in vivo or in ovo models.
Currently, studying the development of the embryonic chicken eye using chemicals is particularly challenging. A number of extraembryonic membranes cover the embryo, making it difficult to apply microbeads or chemicals; the embryo is also very active within the egg as it gets older, further complicating an already difficult method. This protocol enables easy access to the eye and its surrounding tissues, eliminating these barriers, while also providing new opportunities to examine the developmental processes within the eye. This protocol was established to study the induction of the scleral ossicles within the embryonic eye.

<table border="0" cellpadding="0" cellspacing="0" style="width:1081px;" width="1082">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">35 mm cell culture petri dishes</td>
			<td style="width:71px;">Corning</td>
			<td style="width:119px;">353001</td>
			<td style="width:676px;">easy grip tissue culture dish, polystyrene, non-pyrogenic</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">100 mm cell culture petri dishes</td>
			<td style="width:71px;">Corning</td>
			<td style="width:119px;">353003</td>
			<td>tissue culture dish, polystyrene, non-pyrogenic</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">paper tissue</td>
			<td style="width:71px;">Kimtech</td>
			<td style="width:119px;">34155</td>
			<td>Kimtech Science Brand Task Wipers, 280 per carton</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">wire mesh</td>
			<td style="width:71px;">n/a</td>
			<td style="width:119px;">n/a</td>
			<td>stainless steel wire mesh (grid size 0.7 mm)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">disposable glass pipettes</td>
			<td style="width:71px;">VWR</td>
			<td style="width:119px;">14673-010</td>
			<td>Borosilicate glass disposable 5 3/4&#34;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">nutrient medium</td>
			<td style="width:71px;">Gibco</td>
			<td style="width:119px;">12591-038</td>
			<td>Fitton-Jackson Modification, [+] L-glutamine with phenol red (BGJB)</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">penicillin-streptomycin</td>
			<td style="width:71px;">Sigma-Aldrich</td>
			<td style="width:119px;">P4458</td>
			<td>10000 units/mL penicillin streptomycin solution stabilised</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">filter paper</td>
			<td style="width:71px;">Whatman</td>
			<td style="width:119px;">1454 090</td>
			<td>semi-porous filter paper 90mm</td>
		</tr>
		<tr height="147">
			<td height="147" style="height:147px;width:216px;">fertilized chicken eggs</td>
			<td style="width:71px;">Dalhousie University Agricultural College</td>
			<td style="width:119px;">n/a</td>
			<td>can be obtained from local farms</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">sodium chloride (NaCl)</td>
			<td style="width:71px;">EMD</td>
			<td style="width:119px;">SX0420-3</td>
			<td>sodium chloride crystals, reagent grade</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">1 L glass bottle</td>
			<td style="width:71px;">VWR</td>
			<td style="width:119px;">89000-240</td>
			<td>1 L pyrex autoclavable glass bottle</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">ethanol</td>
			<td style="width:71px;">Fisher Scientific</td>
			<td>BP82011</td>
			<td>70% molecular biology grade</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">tupperware containers</td>
			<td style="width:71px;">n/a</td>
			<td style="width:119px;">n/a</td>
			<td>store-bought and sterilized with EtOH</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">disposable razor blades</td>
			<td style="width:71px;">VWR</td>
			<td style="width:119px;">55411-050</td>
			<td>single edge industrial razor blades (surgical carbon steel)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">plastic spoons</td>
			<td style="width:71px;">n/a</td>
			<td style="width:119px;">n/a</td>
			<td>store-bought and sterilized with EtOH</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">dust mask</td>
			<td style="width:71px;">3M</td>
			<td style="width:119px;">n/a</td>
			<td>3M 8500 Comfort Mask</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">paraformaldehyde</td>
			<td style="width:71px;">Sigma-Aldrich</td>
			<td style="width:119px;">P6148</td>
			<td>paraformaldehyde, reagent grade, crystalline</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">neutral-buffered formalin</td>
			<td style="width:71px;">Fisher Scientific</td>
			<td style="width:119px;">72210</td>
			<td>10% neutral buffered formalin</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">phosphate buffered saline (PBS)</td>
			<td style="width:71px;">n/a</td>
			<td style="width:119px;">n/a</td>
			<td>10X phosphate buffered saline pH 7.4 (137mM NaCl, 2.5mM KCl, 4.3mM Na2HPO4, 1.4mM KH2PO4)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">15 ml falcon tubes</td>
			<td style="width:71px;">VWR</td>
			<td style="width:119px;">21008-216</td>
			<td>presterilized centrifuge tubes</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">forceps</td>
			<td style="width:71px;">FST</td>
			<td style="width:119px;">n/a</td>
			<td>fine forceps</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">chick saline&#160;</td>
			<td style="width:71px;">n/a</td>
			<td style="width:119px;">n/a&#160;</td>
			<td>0.85% NaCl</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">tinfoil</td>
			<td style="width:71px;">n/a</td>
			<td style="width:119px;">n/a</td>
			<td>store-bought</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">paper towel</td>
			<td style="width:71px;">n/a</td>
			<td style="width:119px;">n/a</td>
			<td>store-bought</td>
		</tr>
	</tbody>
</table>

organotypic culture method to study the development of embryonic chicken tissues

The embryonic chicken is commonly used as a reliable model organism for vertebrate development. Its accessibility and short incubation period makes it ideal for experimentation. Currently, the study of these developmental pathways in the chicken embryo is conducted by applying inhibitors and drugs at localized sites and at low concentrations using a variety of methods. In vitro tissue&#160;culturing is a technique that enables the study of tissues separated from the host organism, while simultaneously bypassing many of the physical limitations present when working with whole embryos, such as the susceptibility of embryos to high doses of potentially lethal chemicals. Here, we present an organotypic culturing protocol for culturing the embryonic chicken half head in vitro, which presents new opportunities for the examination of developmental processes beyond the currently established methods.

Using this method, an embryonic chicken eye can be cultured from day 8 of its development (HH34) in vitro for 4 days. Four days of in ovo development corresponds to HH38.
This culturing method supports the development of feather buds surrounding the eye and&#160;on the eyelids (Figure 1B). These feather buds are not present in ovo at HH34 prior to the culturing (<strong cl...

Watch this Scientific Journal Video about Organotypic Culture Method to Study the Development Of Embryonic Chicken Tissues at JoVE.com

Organotypic Culture Method to Study the Development Of Embryonic Chicken Tissues

Here, we present an organotypic culturing protocol to grow embryonic chicken organs in vitro. Using this method, the development of embryonic chicken tissue can be studied, while maintaining a high degree of control over the culture environment.

The embryonic chicken is commonly used as a reliable model organism for vertebrate development. Its accessibility and short incubation period makes it ...

organotypic-culture-method-to-study-development-embryonic-chicken

Research

JoVE Journal

Developmental Biology

5.9K Views.  Mount Saint Vincent University. Here, we present an organotypic culturing protocol to grow embryonic chicken organs in vitro. Using this method, the development of embryonic chicken tissue can be studied, while maintaining a high degree of control over the culture environment.

Video: Organotypic Culture Method to Study the Development Of Embryonic Chicken Tissues

Culture of Embryonic Mouse Cochlear Explants and Gene Transfer by Electroporation

Auditory hair cells located within the mouse organ of Corti detect and transmit sound information to the central nervous system. The mechanosensory hair cells are aligned in one row of inner hair cells and three rows of outer hair cells that extend along the basal to apical axis of the cochlea. The explant culture technique described here provides an efficient method to isolate and maintain cochlear explants from the embryonic mouse inner ear. Also, the morphology and molecular characteristics of sensory hair cells and nonsensory supporting cells within the cochlear explant cultures resemble those observed in vivo and can be studied within its intrinsic cellular environment. The cochlear explants can serve as important experimental tools for the identification and characterization of molecular and genetic pathways that are involved in cellular specification and patterning. Although transgenic mouse models provide an effective approach for gene expression studies, a considerable number of mouse mutants die during embryonic development thereby hindering the analysis and interpretation of developmental phenotypes. The organ of Corti from mutant mice that die before birth can be cultured so that their in vitro development and responses to different factors can be analyzed. Additionally, we describe a technique for electroporating embryonic cochlear explants ex vivo which can be used to downregulate or overexpress specific gene(s) and analyze their potential endogenous function and test whether specific gene product is necessary or sufficient in a given context to influence mammalian cochlear development1-8.

We present a method that describes isolation and culture of cochlear explants from embryonic mouse inner ear. We also demonstrate a method for gene transfer into cochlear explants via square-wave electroporation. The in vitro explant culture coupled with gene transfer technique enables researchers to study the effects of altering gene expression during development.

Auditory hair cells located within the mouse organ of Corti detect and transmit sound information to the central nervous system. The mechanosensory hair ...

Manipulation and In Vitro Maturation of Xenopus laevis Oocytes, Followed by Intracytoplasmic Sperm Injection, to Study Embryonic Development

Amphibian eggs have been widely used to study embryonic development. Early embryonic development is driven by maternally stored factors accumulated during oogenesis. In order to study roles of such maternal factors in early embryonic development, it is desirable to manipulate their functions from the very beginning of embryonic development. Conventional ways of gene interference are achieved by injection of antisense oligonucleotides (oligos) or mRNA into fertilized eggs, enabling under- or over-expression of specific proteins, respectively. However, these methods normally require more than several hours until protein expression is affected, and, hence, the interference of gene functions is not effective during early embryonic stages. Here, we introduce an experimental system in which expression levels of maternal proteins can be altered before fertilization. Xenopus laevis oocytes obtained from ovaries are defolliculated by incubating with enzymes. Antisense oligos or mRNAs are injected into defolliculated oocytes at the germinal vesicle (GV) stage. These oocytes are in vitro matured to eggs at the metaphase II (MII) stage, followed by intracytoplasmic sperm injection (ICSI). By this way, up to 10% of ICSI embryos can reach the swimming tadpole stage, thus allowing functional tests of specific gene knockdown or overexpression. This approach can be a useful way to study roles of maternally stored factors in early embryonic development.

Manipulation and In Vitro Maturation of Xenopus laevis Oocytes, Followed by Intracytoplasmic Sperm Injection, to Study Embryonic Development

We describe methods of manipulating Xenopus laevis immature oocytes, in vitro maturation of oocytes to eggs, and intracytoplasmic sperm injection. This protocol allows degradation of some maternal proteins and overexpression of genes of interest at fertilization, and hence is valuable to study roles of specific factors in early embryonic development.

Amphibian eggs have been widely used to study embryonic development. Early embryonic development is driven by maternally stored factors accumulated during ...

Transcriptome Profiling of In-Vivo Produced Bovine Pre-implantation Embryos Using Two-color Microarray Platform

Early embryonic loss is a large contributor to infertility in cattle. Moreover, bovine becomes an interesting model to study human preimplantation embryo development due to their similar developmental process. Although genetic factors are known to affect early embryonic development, the discovery of such factors has been a serious challenge. Microarray technology allows quantitative measurement and gene expression profiling of transcript levels on a genome-wide basis. One of the main decisions that have to be made when planning a microarray experiment is whether to use a one- or two-color approach. Two-color design increases technical replication, minimizes variability, improves sensitivity and accuracy as well as allows having loop designs, defining the common reference samples. Although microarray is a powerful biological tool, there are potential pitfalls that can attenuate its power. Hence, in this technical paper we demonstrate an optimized protocol for RNA extraction, amplification, labeling, hybridization of the labeled amplified RNA to the array, array scanning and data analysis using the two-color analysis strategy.

Transcriptome Profiling of In-Vivo Produced Bovine Pre-implantation Embryos Using Two-color Microarray Platform

Microarray technology allows quantitative measurement and gene expression profiling of transcripts on a genome-wide basis. Therefore, this protocol provides an optimized technical procedure in a two-color custom made bovine array using Day 7 bovine embryos to demonstrate the feasibility of using low amount of total RNA.

Early embryonic loss is a large contributor to infertility in cattle. Moreover, bovine becomes an interesting model to study human preimplantation embryo ...

Epigenetic Regulation of Cardiac Differentiation of Embryonic Stem Cells and Tissues

Specific gene transcription is a key biological process that underlies cell fate decision during embryonic development. The biological process is mediated by transcription factors which bind genomic regulatory regions including enhancers and promoters of cardiac constitutive genes. DNA is wrapped around histones that are subjected to chemical modifications. Modifications of histones further lead to repressed, activated or poised gene transcription, thus bringing another level of fine tuning regulation of gene transcription. Embryonic Stem cells (ES cells) recapitulate within embryoid bodies (i.e., cell aggregates) or in 2D culture the early steps of cardiac development. They provide in principle enough material for chromatin immunoprecipitation (ChIP), a technology broadly used to identify gene regulatory regions. Furthermore, human ES cells represent a human cell model of cardiogenesis. At later stages of development, mouse embryonic tissues allow for investigating specific epigenetic landscapes required for determination of cell identity. Herein, we describe protocols of ChIP, sequential ChIP followed by PCR or ChIP-sequencing using ES cells, embryoid bodies and cardiac specific embryonic regions. These protocols allow to investigating the epigenetic regulation of cardiac gene transcription.

A fine tuning regulation of gene transcription underlies embryonic cell fate decision. Herein, we describe chromatin immunoprecipitation assays used to investigate epigenetic regulation of both cardiac differentiation of stem cells and cardiac development of mouse embryos.

Specific gene transcription is a key biological process that underlies cell fate decision during embryonic development. The biological process is mediated ...

A Novel Ex Ovo Banding Technique to Alter Intracardiac Hemodynamics in an Embryonic Chicken System

The new model presented here can be used to understand the influence of hemodynamics on specific cardiac developmental processes, at the cellular and molecular level. To alter intracardiac hemodynamics, fertilized chicken eggs are incubated in a humidified chamber to obtain embryos of the desired stage (HH17). Once this developmental stage is achieved, the embryo is maintained ex ovo and hemodynamics in the embryonic heart are altered by partially constricting the outflow tract (OFT) with a surgical suture at the junction of the OFT and ventricle (OVJ). Control embryos are also cultured ex ovo but are not subjected to the surgical intervention. Banded and control embryos are then incubated in a humidified incubator for the desired period of time, after which 2D ultrasound is employed to analyze the change in blood flow velocity at the OVJ as a result of OFT banding. Once embryos are maintained ex ovo, it is important to ensure adequate hydration in the incubation chamber so as to prevent drying and eventually embryo death. Using this new banded model, it is now possible to perform analyses of changes in the expression of key players involved in valve development and to understand the role of hemodynamics on cellular responses in vivo, which could not be achieved previously.

A Novel Ex Ovo Banding Technique to Alter Intracardiac Hemodynamics in an Embryonic Chicken System

For the first time we present here a reproducible banding procedure to alter hemodynamics in the developing heart ex ovo. This is achieved by partially constricting the outflow tract (OFT).

The new model presented here can be used to understand the influence of hemodynamics on specific cardiac developmental processes, at the cellular and ...

Culture of Murine Embryonic Metatarsals: A Physiological Model of Endochondral Ossification

The fundamental process of endochondral ossification is under tight regulation in the healthy individual so as to prevent disturbed development and/or longitudinal bone growth. As such, it is imperative that we further our understanding of the underpinning molecular mechanisms involved in such disorders so as to provide advances towards human and animal patient benefit. The mouse metatarsal organ explant culture is a highly physiological ex vivo model for studying endochondral ossification and bone growth as the growth rate of the bones in culture mimic that observed in vivo. Uniquely, the metatarsal organ culture allows the examination of chondrocytes in different phases of chondrogenesis and maintains cell-cell and cell-matrix interactions, therefore providing conditions closer to the in vivo situation than cells in monolayer or 3D culture. This protocol describes in detail the intricate dissection of embryonic metatarsals from the hind limb of E15 murine embryos and the subsequent analyses that can be performed in order to examine endochondral ossification and longitudinal bone growth.

We present a protocol to dissect and culture embryonic day 15 (E15) murine metatarsal bones. This highly physiological ex vivo model of endochondral ossification provides conditions closer to the in vivo situation than cells in monolayer or 3D culture and is a vital tool for investigating bone growth and development.

The fundamental process of endochondral ossification is under tight regulation in the healthy individual so as to prevent disturbed development and/or ...

Dissection and Culture of Mouse Embryonic Kidney

The goal of this protocol is to describe a method for the dissection, isolation, and culture of mouse metanephric rudiments. 
During mammalian kidney development, the two progenitor tissues, the ureteric bud and the metanephric mesenchyme, communicate and reciprocally induce cellular mechanisms to eventually form the collecting system and the nephrons of the kidney. As mammalian embryos grow intrauterine and therefore are inaccessible to the observer, an organ culture has been developed. With this method, it is possible to study epithelial-mesenchymal interactions and cellular behavior during kidney organogenesis. Furthermore, the origin of congenital kidney and urogenital tract malformations can be investigated. After careful dissection, the metanephric rudiments are transferred onto a filter that floats on culture medium and can be kept in a cell culture incubator for several days. However, one must be aware that the conditions are artificial and could influence the metabolism in the tissue. Also, the penetration of test substances could be limited due to the extracellular matrix and basal membrane present in the explant.
One main advantage of organ culture is that the experimenter can gain direct access to the organ. This technology is cheap, simple, and allows a large number of modifications, such as the addition of biologically active substances, the study of genetic variants, and the application of advanced imaging techniques.

This protocol describes a method for isolating and culturing metanephric rudiments from mouse embryos.

The goal of this protocol is to describe a method for the dissection, isolation, and culture of mouse metanephric rudiments. 
During mammalian kidney ...

Computational Analysis of the Caenorhabditis elegans Germline to Study the Distribution of Nuclei, Proteins, and the Cytoskeleton

The Caenorhabditis elegans (C. elegans) germline is used to study several biologically important processes including stem cell development, apoptosis, and chromosome dynamics. While the germline is an excellent model, the analysis is often two dimensional due to the time and labor required for three-dimensional analysis. Major readouts in such studies are the number/position of nuclei and protein distribution within the germline. Here, we present a method to perform automated analysis of the germline using confocal microscopy and computational approaches to determine the number and position of nuclei in each region of the germline. Our method also analyzes germline protein distribution that enables the three-dimensional examination of protein expression in different genetic backgrounds. Further, our study shows variations in cytoskeletal architecture in distinct regions of the germline that may accommodate specific spatial developmental requirements. Finally, our method enables automated counting of the sperm in the spermatheca of each germline. Taken together, our method enables rapid and reproducible phenotypic analysis of the C. elegans germline.

Computational Analysis of the Caenorhabditis elegans Germline to Study the Distribution of Nuclei, Proteins, and the Cytoskeleton

We present an automated method for three-dimensional reconstruction of the Caenorhabditis elegans germline. Our method determines the number and position of each nucleus within the germline and analyses germline protein distribution and cytoskeletal structure.

The Caenorhabditis elegans (C. elegans) germline is used to study several biologically important processes including stem cell development, apoptosis, and ...

Isolation of Embryonic Tissues and Formation of Quail-Chicken Chimeric Organs Using The Thymus Example

The capacity to isolate embryonic tissues was an essential step for establishing the quail-chicken chimera system, which in turn has provided undisputed contributions to unveiling key processes in developmental biology.
Herein is described an optimized method to isolate embryonic tissues from quail and chickens by microsurgery and enzymatic digestion while preserving its biological properties. After isolation, tissues from both species are associated in an in vitro organotypic assay for 48 h. Quail and chicken tissues can be discriminated by distinct nuclear features and molecular markers allowing the study of the cellular cross-talk between heterospecific association of tissues. This approach is, therefore, a useful tool for studying complex tissue interactions in developmental processes with highly dynamic spatial modifications, such as those occurring during pharyngeal morphogenesis and the formation of the foregut endoderm-derived organs. This experimental approach was first developed to study the epithelial-mesenchymal interactions during early-stages of thymus formation. In this, the endoderm-derived prospective thymic rudiment and mesoderm-derived mesenchyme, were isolated from quail and chicken embryos, respectively.
The capacity of the associated tissues to generate organs can be further tested by grafting them onto the chorioallantoic membrane (CAM) of a chicken embryo. The CAM provides nutrients and allows gas exchanges to the explanted tissues. After 10 days of in ovo development, the chimeric organs can be analyzed in the harvested explants by conventional morphological methods. This procedure also allows studying tissue-specific contributions during organ formation, from its initial development (in vitro development) to the final stages of organogenesis (in ovo development).
Finally, the improved isolation method also provides three-dimensionally (3D) preserved embryonic tissues, that can also be used for high-resolution topographical analysis of tissue-specific gene-expression patterns.

This article provides a method to isolate pure embryonic tissues from quail and chicken embryos that can be combined to form ex vivo chimeric organs.

The capacity to isolate embryonic tissues was an essential step for establishing the quail-chicken chimera system, which in turn has provided undisputed ...

A Semi-high-throughput Imaging Method and Data Visualization Toolkit to Analyze C. elegans Embryonic Development

C. elegans is the premier system for the systematic analysis of cell fate specification and morphogenetic events during embryonic development. One challenge is that embryogenesis dynamically unfolds over a period of about 13 h; this half day-long timescale has constrained the scope of experiments by limiting the number of embryos that can be imaged. Here, we describe a semi-high-throughput protocol that allows for the simultaneous 3D time-lapse imaging of development in 80&#8211;100 embryos at moderate time resolution, from up to 14 different conditions, in a single overnight run. The protocol is straightforward and can be implemented by any laboratory with access to a microscope with point visiting capacity. The utility of this protocol is demonstrated by using it to image two custom-built strains expressing fluorescent markers optimized to visualize key aspects of germ-layer specification and morphogenesis. To analyze the data, a custom program that crops individual embryos out of a broader field of view in all channels, z-steps, and timepoints and saves the sequences for each embryo into a separate tiff stack was built. The program, which includes a user-friendly graphical user interface (GUI), streamlines data processing by isolating, pre-processing, and uniformly orienting individual embryos in preparation for visualization or automated analysis. Also supplied is an ImageJ macro that compiles individual embryo data into a multi-panel file that displays maximum intensity fluorescence projection and brightfield images for each embryo at each time point. The protocols and tools described herein were validated by using them to characterize embryonic development following knock-down of 40 previously described developmental genes; this analysis visualized previously annotated developmental phenotypes and revealed new ones. In summary, this work details a semi-high-throughput imaging method coupled with a cropping program and ImageJ visualization tool that, when combined with strains expressing informative fluorescent markers, greatly accelerates experiments to analyze embryonic development.

A Semi-high-throughput Imaging Method and Data Visualization Toolkit to Analyze C. elegans Embryonic Development

This work describes a semi-high-throughput protocol that allows simultaneous 3D time-lapse imaging of embryogenesis in 80&#8211;100 C. elegans embryos in a single overnight run. Additionally, image processing and visualization tools are included to streamline data analysis. The combination of these methods with custom reporter strains enables detailed monitoring of embryogenesis.