1. Ex-ovo Culture Protocol:
<ol>
	<li>Incubate fertilized chicken eggs
	<ol class="lroman">
		<li>Fertilized chicken eggs can be stored at 13&deg;C up to 5 days before incubation without initiating development. A red wine cooler can maintain this temperature.</li>
		<li>Incubate eggs blunt side up in a 60% constant humidity incubator with continuous rocking at 37.5&deg;C for 72 hours.</li>
 </ol>
 </li>
 <li>Prepare hammocks (Figure 1a)
	<ol class="lroman">
		<li>Fill &frac34; of 9 oz plastic cups with warm sterile water. A regular 9 oz cup has a top diameter of 8 cm. We found that this size was most suitable for long time culture application presented here.</li>
		<li>Cut about 20 cm cling wrap. Affix circumferentially on top of the cup by placing a rubber band around. Plastic should be spread on top of the water. Cut the excess plastic around the band. We found cling wrap to be most appropriate for this application since it prevents adhesion of the yolk, resulting in the yolk splitting during transportation.</li>
		<li>Wipe the plastic with kimwipes (Kimberly-Clark, Inc.) wetted with 70% ethanol.</li>
	</ol>
 </li>
	<li>Remove eggs from incubator after 72 hours of incubation.</li>
	<li>Sterilize eggs by wiping surface with 70% ethanol wetted kimwipes.</li>
	<li>Lay the eggs horizontally for 1-2 minutes for proper positioning of the embryo (Figure 1b). An egg carton can be used for laying eggs horizontally. Embryos will rotate to the top after 1-2 minutes.</li>
	<li>Transfer embryos onto hammocks aseptically in a laminar flow hood.
	<ol class="lroman">
 	<li>Using a sharp edge (like the edge of a metal bucket or a glass beaker), tap the egg gently until there is a small dent on the underside of the egg (Figure 1c). Remember, the embryo is positioned on the upperside.</li>
		<li>Put thumbs in opposite sides of the dent and pull the shells apart horizontally (Figure 1d).</li>
		<li>Place the yolk with embryo as well as albumin onto the hammock (figure 1e). Albumin will provide a dampening environment around the yolk to absorb shocks induced by moving the system as well as it provides nutrition to the embryo for long culture practices. Water underneath the hammock will ensure the embryo will stay parallel to the ground during transport and serve as a conductor of heat during imaging if a water circulation heater is used.</li>
		<li>The embryo should already be positioned on top if the transfer is performed properly. If not, use an unsharp, sterile object (ie. Blunt tip of closed curved scissors) and directionally caress the yolk such that the embryo rotates to the top.</li>
		<li>Place a 10 cm diameter Petri dish on top of the cup to seal the embryo.</li>
	</ol>
 </li>
	<li>Place cup culture into the incubator set at 37.5&deg;C. If a portable incubator is used, placing 1-2 9 oz cups filled with distilled water keeps the humidity at ~60% (Figure 1f).</li>
	<li>If culturing embryos beyond embryonic day 7, crushed eggshell pieces should be scattered around the periphery of the embryo as a calcium source for bone development and maturation.</li>
</ol>
Accessory equipment for outside incubator imaging/ manipulation:
A circulating water bath was built in house to maintain incubation temperatures while imaging or manipulation (Figure 3). A water bath that can fit the cup is connected via appropriate size tubing to a water reservoir. A resistance heater heats the water in the reservoir which is regulated manually by following the water temperature. A water pump circulates the water. Pictoral representation depicts imaging ease via ultrasongraphy/florescent microscopy (Figure 3).
<img src="/files/ftp_upload/2154/2125fig1.jpg" alt="Figure 1" /> Figure 1. Preparation of hammock and transfer of chicken embryos to hammocks.
<img src="/files/ftp_upload/2154/2125fig2.jpg" alt="Figure 2" /> Figure 2. Representative results - different stage chicken embryos grown via ex ovo culture technique. Embryos from HH 17 onwards can be grown via this technique.
<img src="/files/ftp_upload/2154/2125fig3.jpg" alt="Figure 3" /> Figure 3. Schematic and representative pictures of the water circulation system used in conjunction with the ex-ovo culture system to keep embryos at ideal development temperature.
2. Selected Applications:
 I. Microinjection
This embryo culture is suitable for microinjection applications where solutions need to be injected to vasculature for contrast based imaging (ie. fluorescent microscopy, micro-computed topography etc.) (Figure 4). Below is the microinjection protocol:
<ol>
	<li>Prepare the injection apparatus
	<ol class="lroman">
		<li>Fashion pulled 0.75 ID glass capillary tubes into beveled tip microneedles using a microforge. Size of the tip required depends on target vein diameter/flow rate desired.</li>
		<li>Connect the syringe to 0.03 inch ID silicone tubing.</li>
		<li>Load the tubing with the solution to be injected and connect the microneedle to the tubing.</li>
		<li>Place the microneedle onto the micromanipulator and syringe to syringe holder or syringe pump.</li>
	</ol>
 </li>
	<li>Add sterile water in the cup thereby raise the embryo. We experienced that for proper penetration of the needle into a blood vessel (ie. vitelline vessel), horizontal penetration is necessary. This requires the embryo to be on the same plane as the edges of the cup.
 <ol class="lroman">
		<li>Take out the rubber band holding the plastic under the embryo.</li>
		<li>Lift one side of the plastic gently and add some sterile water to the cup.</li>
		<li>Secure the rubber band onto the plastic again.</li>
	</ol>
 </li>
	<li>Inject the solution to an embryonic vessel. In our experience, when solution is injected to a vitelline vessel, microneedles needed to be sized approximately 1/10th of the vessel diameter to maintain efficient perfusion without causing bleeding.
<ol class="lroman">
	<li>Pump the solution to the microneedle ensuring no formation of air bubbles.</li>
	<li>Align the tip of the microneedle onto the selected vessel. For vitelline vessels, selecting a fork area will give maximum area to penetrate the vessel.</li>
	<li>Push the needle towards the vessel. The vessel will first retract. Once the needle penetrates, start perfusion. The color of the flowing blood should change with perfusion. If color change is not seen, the needle may have penetrated out of the vessel. In that case, slowly retract the microneedle while simultaneously pumping solution till color change in the vessel is seen. Once the perfusion is complete, retract the microneedle out of the vessel.</li>
</ol>
</li>
</ol>
<img src="/files/ftp_upload/2154/2125fig4.jpg" alt="Figure 4" /> Figure 4: Microinjection of a fluorescent dye into the vasculature of an ex-ovo cultured chick embryo.
II. Microsurgical Procedure - Left Atrial Ligation
This ex-ovo culture setup is ideal for performing surgical applications to chick embryos since it provides full accessibility to the embryo. Below is the protocol for an example technique, left atrial ligation (LAL) (Figure 5). The procedure is performed approximately 24 hours into the culture period (HH24):
<ol>
	<li>Prepare overhand knots ~0.5 mm diameter using 10-0 nylon surgical suture.</li>
	<li>With fine forceps, locally remove the chorionic and allantoic membranes over the embryo and lift the embryo from the back to rotate it vertically such that the left side of the embryo is visible.</li>
	<li>Using fine forceps, remove the pericardium over the left atrium.</li>
	<li>Align the knot over the left atrium and tighten it. The knot should be tied so as to prohibit ~75% of the original blood flow to the left side. Cut the edges of the knot with microscissors and carefully remove and discard excess suture.</li>
	<li>Rotate the embryo back to its original orientation (right side on top).</li>
	<li>Sham controls will involve the same procedure but the suture will just be passed through and not tied. Effective LAL treatment (75% constriction) will be confirmed at 24 hours post-surgery, and disqualified embryos will be excluded.</li>
</ol>
<img src="/files/ftp_upload/2154/2154fig5.jpg" alt="Figure 5" /> Figure 5: A control and a left atrial ligated chick embryo. Arrow shows the left atria, which is about 75% smaller in the ligated embryo.

<ol>
	<li>Zamir, E. A., Czirok, A., Cui, C., Little, C. D., Rongish, B. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mesodermal+cell+displacements+during+avian+gastrulation+are+due+to+both+individual+cell-autonomous+and+convective+tissue+movements.">Mesodermal cell displacements during avian gastrulation are due to both individual cell-autonomous and convective tissue movements.</a> Proc Natl Acad Sci U S A. 103, 19806-19811 (1980).</li><li>Ehrman, L. A., Yutzey, K. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lack+of+regulation+in+the+heart+forming+region+of+avian+embryos.">Lack of regulation in the heart forming region of avian embryos.</a> Dev Biol. 207, 163-175 (1999).</li><li>Clark, E. B., Hu, N., Rosenquist, G. C. <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+conotruncal+constriction+on+aortic-mitral+valve+continuity+in+the+stage+18,+21+and+24+chick+embryo.">Effect of conotruncal constriction on aortic-mitral valve continuity in the stage 18, 21 and 24 chick embryo.</a> Am J Cardiol. 53, 324-327 (1984).</li><li>deAlmeida, A., McQuinn, T., Sedmera, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Increased+ventricular+preload+is+compensated+by+myocyte+proliferation+in+normal+and+hypoplastic+fetal+chick+left+ventricle.">Increased ventricular preload is compensated by myocyte proliferation in normal and hypoplastic fetal chick left ventricle.</a> Circ Res. 100, 1363-1370 (2007).</li><li>Nakamura, H., Funahashi, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Introduction+of+DNA+into+chick+embryos+by+in+ovo+electroporation.">Introduction of DNA into chick embryos by in ovo electroporation.</a> Methods. 24, 43-48 (2001).</li><li>Butcher, J. T., McQuinn, T. C., Sedmera, D., Turner, D., Markwald, R. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transitions+in+early+embryonic+atrioventricular+valvular+function+correspond+with+changes+in+cushion+biomechanics+that+are+predictable+by+tissue+composition.">Transitions in early embryonic atrioventricular valvular function correspond with changes in cushion biomechanics that are predictable by tissue composition.</a> Circ Res. 100, 1503-1511 (2007).</li><li>McQuinn, T. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-frequency+ultrasonographic+imaging+of+avian+cardiovascular+development.">High-frequency ultrasonographic imaging of avian cardiovascular development.</a> Dev. Dyn. 236, 3503-3513 (2007).</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> J Vis Exp. , (2007).</li><li>Auerbach, R., Kubai, L., Knighton, D., Folkman, J. <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+procedure+for+the+long-term+cultivation+of+chicken+embryos.">A simple procedure for the long-term cultivation of chicken embryos.</a> Dev Biol. 41, 391-394 (1974).</li></ol>

No conflicts of interest declared.

Optical access and experimentation in avian embryos is challenging due to constraints of the egg shell. Windowing significantly limits the number of microvessels accessible for injection and microsurgical approaches8. As a result only early embryos can be manipulated and continuous observation is not possible. Early ex-ovo cultures using Petri dishes were of limited use because of inadequate control of the surface tension on the embryo prevented long term culture9. We recently improved ...

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		<div>
		<table border="1">
		<thead>
		<tr>
		<th>Material Name</th>
		<th>Type</th>
		<th>Company</th>
		<th>Catalogue Number</th>
		<th>Comment</th>
		</tr>
		</thead>
		<tbody>
		
<tr>
<td>Fertile white Leghorn chicken eggs</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Model GB1, Avery Incubators, Hugo CO</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Saran Wrap</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Kimwipes</td>
<td>&nbsp;</td>
<td>Kimberly-Clark, Inc.</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Rubber bands</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Warm sterile water</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>9 oz plastic cup</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>100 mm diameter Petri dish</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>1602N thermal air</td>
<td>&nbsp;</td>
<td>GQF Manufacturing CO, Savannah GA</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Fluorescein-conjugated dextran (2 MDa, 1% w/v in phosphate buffered saline)</td>
<td>&nbsp;</td>
<td>Sigma Aldrich Inc.</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Microforge</td>
<td>&nbsp;</td>
<td>Glassworx, Inc, St Louis MO</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Glass capillary tubes (0.75 mm ID)</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Micromanipulator</td>
<td>&nbsp;</td>
<td>World Precision Instruments, Sarasota FL</td>
<td>Model M3301L</td>
<td>&nbsp;</td>
<tr>
<td>Fluorescent microscopy</td>
<td>&nbsp;</td>
<td>Zeiss</td>
<td>Z20</td>
<td>&nbsp;</td>
<tr>
<td>Fine 55-forceps</td>
<td>&nbsp;</td>
<td>World Precision Instruments, Sarasota FL</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>10-0 nylon surgical suture</td>
<td>&nbsp;</td>
<td>Ethicon</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Tubing</td>
<td>&nbsp;</td>
<td>VWR</td>
<td>&nbsp;</td>
<td>1mm OD</td>
</tr>
<tr>
<td>3 mL syringe</td>
<td>&nbsp;</td>
<td>BD</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>200 &mu;L pipetter and pipette tips</td>
<td>&nbsp;</td>
<td>VWR</td>
<td>&nbsp;</td>
<td>&nbsp;</td>		</tbody>
		</table>
		</div>

an ex-ovo chicken embryo culture system suitable for imaging and microsurgery applications

Understanding the relationships between genetic and microenvironmental factors that drive normal and malformed embryonic development is fundamental for discovering new therapeutic strategies. Advancements in imaging technology have enabled quantitative investigation of the organization and maturing of the body plan, but later stage embryonic morphogenesis is less clear. Chicken embryos are an attractive vertebrate animal model system for this application because of its ease of culture and surgical manipulation. Early embryos can be cultured for a short time on filter paper rings, which enables complete optical access for cell patterning and fate studies1,2. Studying advanced developmental processes such as cardiac morphogenesis are traditionally performed through a window of the eggshell3-5, but this technique limits optical access due to window size. We previously developed a simple method to culture whole embryos ex-ovo on hexagonal weigh boats for up to 10 days, which enabled high resolution imaging via ultrasonography6,7. These cultures were difficult to transport, limiting the types of imaging tools available for live experiments. We here present an improved shell-less culture system with a cost-effective, portable environmental chamber. Eggs were cracked onto a hammock created by a polyurethane membrane (cling wrap) affixed circumferentially to a plastic cup partially filled with sterile water. The dimensions of the circumference and depth of the hammock were both critical to maintain surface tension, while the mechanics of the hammock and water beneath helped dampen vibrations induced by transportation. A small footprint circulating water bath was also developed to enable continuous temperature control during experimentation. We demonstrate the ability to culture embryos in this way for at least 14 days without morphogenic defect or delay and employ this system in several microsurgical and imaging applications.

Watch this Scientific Journal Video about An ex-ovo Chicken Embryo Culture System Suitable for Imaging and Microsurgery Applications at JoVE.com

An ex-ovo Chicken Embryo Culture System Suitable for Imaging and Microsurgery Applications

In this article, we present a simple methodology to enable long-term ex-ovo avian embryo culture. This technique is ideal for longitudinal experimentation requiring complete optical accessibility and/or sterile transportation in avian embryos.

An ex-ovo Chicken Embryo Culture System Suitable for Imaging and Microsurgery Applications

Understanding the relationships between genetic and microenvironmental factors that drive normal and malformed embryonic development is fundamental for ...

an-ex-ovo-chicken-embryo-culture-system-suitable-for-imaging

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22.9K Views.  Cornell University. In this article, we present a simple methodology to enable long-term ex-ovo avian embryo culture. This technique is ideal for longitudinal experimentation requiring complete optical accessibility and/or sterile transportation in avian embryos.

Video: An ex-ovo Chicken Embryo Culture System Suitable for Imaging and Microsurgery Applications

Bioelectric Analyses of an Osseointegrated Intelligent Implant Design System for Amputees

The projected number of American amputees is expected to rise to 3.6 million by 2050.  Many of these individuals depend on artificial limbs to perform routine activities, but prosthetic suspensions using traditional socket technology can prove to be cumbersome and uncomfortable for a person with limb loss.  Moreover, for those with high proximal amputations, limited residual limb length may prevent exoprosthesis attachment all together. Osseointegrated implant technology is a novel operative procedure which allows firm skeletal attachment between the host bone and an implant. Preliminary results in European amputees with osseointegrated implants have shown improved clinical outcomes by allowing direct transfer of loads to the bone-implant interface.  Despite the apparent advantages of osseointegration over socket technology, the current rehabilitation procedures require long periods of restrictive load bearing prior which may be reduced with expedited skeletal attachment via electrical stimulation.  The goal of the osseointegrated intelligent implant design (OIID) system is to make the implant part of an electrical system to accelerate skeletal attachment and help prevent periprosthetic infection. To determine optimal electrode size and placement, we initiated proof of concept with computational modeling of the electric fields and current densities that arise during electrical stimulation of amputee residual limbs.  In order to provide insure patient safety, subjects with retrospective computed tomography scans were selected and three dimensional reconstructions were created using customized software programs to ensure anatomical accuracy (Seg3D and SCIRun) in an IRB and HIPAA approved study.  These software packages supported the development of patient specific models and allowed for interactive manipulation of electrode position and size. Preliminary results indicate that electric fields and current densities can be generated at the implant interface to achieve the homogenous electric field distributions   required to induce osteoblast migration, enhance skeletal fixation and may help prevent periprosthetic infections.  Based on the electrode configurations experimented with in the model, an external two band configuration will be advocated in the future.

There is a need to develop alternative prosthesis attachment due to limb loss attributed to vascular occlusive diseases and trauma. The goal of the work is to introduce an osseointegrated intelligent implant design system to increase skeletal fixation and reduce periprosthetic infection rates for patients needing osseointegrated technology.

The projected number of American amputees is expected to rise to 3.6 million by 2050.  Many of these individuals depend on artificial limbs to perform ...

Chick ex ovo Culture and ex ovo CAM Assay: How it Really Works

Chicken eggs in the early phase of breeding are between in vitro and in vivo systems and provide a vascular test environment not only to study angiogenesis but also to study tumorigenesis. After the chick chorioallantoic membrane (CAM) has developed, its blood vessel network can be easily accessed, manipulated and observed and therefore provides an optimal setting for angiogenesis assays. Since the lymphoid system is not fully developed until late stages of incubation, the chick embryo serves as a naturally immunodeficient host capable of sustaining grafted tissues and cells without species-specific restrictions. In addition to nurturing developing allo- and xenografts, the CAM blood vessel network provides a uniquely supportive environment for tumor cell intravasation, dissemination, and vascular arrest and a repository where arrested cells extravasate to form micro metastatic foci.
For experimental purposes, in most of the recent studies the CAM was exposed by cutting a window through the egg shell and experiments were carried out in ovo, resulting in significant limitations in the accessibility of the CAM and possibilities for observation and photo documentation of effects. When shell-less cultures of the chick embryo were used1-4, no experimental details were provided and, if published at all, the survival rates of these cultures were low. We refined the method of ex ovo culture of chick embryos significantly by introducing a rationally controlled extrusion of the egg content. These ex ovo cultures enhance the accessibility of the CAM and chick embryo, enabling easy in vivo documentation of effects and facilitating experimental manipulation of the embryo. This allows the successful application to a large number of scientific questions: (1) As an improved angiogenesis assay5,6, (2) an experimental set up for facilitated injections in the vitreous of the chick embryo eye7-9, (3) as a test environment for dissemination and intravasation of dispersed tumor cells from established cell lines inoculated on the CAM10-12, (4) as an improved sustaining system for successful transplantation and culture of limb buds of chicken and mice13 as well as (5) for grafting, propagation, and re-grafting of solid primary tumor tissue obtained from biopsies on the surface of the CAM14.
In this video article we describe the establishment of a refined chick ex ovo culture and CAM assay with survival rates over 50%. Besides we provide a step by step demonstration of the successful application of the ex ovo culture for a large number of scientific applications. 
Daniel S. Dohle, Susanne D. Pasa, and Sebastian Gustmann contributed equally to this study.

Chick ex ovo Culture and ex ovo CAM Assay: How it Really Works

The chick chorioallantoic membrane (CAM) is a unique, naturally immunodeficient supportive culture environment to study angiogenesis and tumorigenesis. This video article demonstrates the different steps in chick ex ovo culture, application of potentially angiogenic substances and successful inoculation of tumor cells and tissues on the surface of the CAM.

Chicken eggs in the early phase of breeding are between in vitro and in vivo systems and provide a vascular test environment not only to study ...

Xenotransplantation of Human Stem Cells into the Chicken Embryo

The chicken embryo is a classical animal model for studying normal embryonic and fetal development and for xenotransplantation experiments to study the behavior of cells in a standardized in vivo environment. The main advantages of the chicken embryo include low cost, high accessibility, ease of surgical manipulation and lack of a fully developed immune system. Xenotransplantation into chicken embryos can provide valuable information about cell proliferation, differentiation and behavior, the responses of cells to signals in defined embryonic tissue niches, and tumorigenic potential. Transplanting cells into chicken embryos can also be a step towards transplantation experiments in other animal models. Recently the chicken embryo has been used to evaluate the neurogenic potential of human stem and progenitor cells following implantation into neural anlage1-6. In this video we document the entire procedure for transplanting human stem cells into the developing central nervous system of the chicken embryo. The procedure starts with incubation of fertilized eggs until embryos of the desired age have developed. The eggshell is then opened, and the embryo contrasted by injecting dye between the embryo and the yolk. Small lesions are made in the neural tube using microsurgery, creating a regenerative site for cell deposition that promotes subsequent integration into the host tissue. We demonstrate injections of human stem cells into such lesions made in the part of the neural tube that forms the hindbrain and the spinal cord, and into the lumen of the part of the neural tube that forms the brain. Systemic injections into extraembryonic veins and arteries are also demonstrated as an alternative way to deliver cells to vascularized tissues including the central nervous system. Finally we show how to remove the embryo from the egg after several days of further development and how to dissect the spinal cord free for subsequent physiological, histological or biochemical analyses.

In this paper we present a method for transplanting human stem cells into various regions of the central nervous system of the chicken embryo. This provides an in vivo model for assessing the proliferation and differentiation of various types of human stem cells in embryonic tissue environments.

The chicken embryo is a classical animal model for studying normal embryonic and fetal development and for xenotransplantation experiments to study the ...

The Method of Rodent Whole Embryo Culture using the Rotator-type Bottle Culture System

Whole embryo culture (WEC) technique has been developed in 1950's by New and his colleagues, and applied for developmental biology 1. Although development and growth of mammalian embryos are critically dependent on the function of the placenta, WEC technique allows us to culture mouse and rat embryos ex vivo condition during limited periods corresponding to midgestation stages during embryonic day (E) 6.5-E12.5 in the mouse or E8.5-E14.5 in the rat 2, 3, 4. In WEC, we can directly target desired areas of embryos using fine glass capillaries because embryos can be manipulated under the microscope. Therefore, rodent WEC is very useful technique when we want to study dynamic developmental processes of postimplanted mammalian embryos. Up to date, several types of WEC systems have been developed 1. Among those, the rotator-type bottle culture system is most popular and suitable for long-term culture of embryos at midgestation, i.e., after E9.5 and E11.5 in the mouse and rat, respectively 1. In this video protocol, we demonstrate our standard procedures of rat WEC after E12.5 using a refined model of the original rotator system, which was designed by New and Cockroft 5, 6, and introduce various applications of WEC technique for studies in mammalian developmental biology.

Whole embryo culture technique allows us to culture mouse and rat embryos ex vivo condition during limited periods corresponding to midgestation stages. In this video protocol, we demonstrate our standard procedures of rat whole embryo culture after E12.5 using the rotator-type bottle culture system.

Whole embryo culture (WEC) technique has been developed in 1950's by New and his colleagues, and applied for developmental biology 1. Although development ...

Closed System Cell Culture Protocol Using HYPERStack Vessels with Gas Permeable Material Technology

Large volume adherent cell culture is currently standardized on stacked plate cell growth products when microcarrier beads are not an optimal choice. HYPERStack vessels allow closed system scale up from the current stacked plate products and delivers >2.5X more cells in the same volumetric footprint. The HYPERStack vessels function via gas permeable material which allows gas exchange to occur, therefore eliminating the need for internal headspace within a vessel. The elimination of headspace allows the compartment where cell growth occurs to be minimized to reduce space, allowing more layers of cell growth surface area within the same volumetric footprint.
For many applications such as cell therapy or vaccine production, a closed system is required for cell growth and harvesting. The HYPERStack vessel allows cell and reagent addition and removal via tubing from media bags or other methods.
This protocol will explain the technology behind the gas permeable material used in the HYPERStack vessels, gas diffusion results to meet the metabolic needs of cells, closed system cell growth protocols, and various harvesting methods.

An Introduction into the technology, protocol and handling of the Corning HYPERStack Vessels and accessories used for high yield adherent cell culture. The protocol will show how to use the closed system vessels for increasing cell harvesting over current stacked plate products.

Large volume adherent cell culture is currently standardized on stacked plate cell growth products when microcarrier beads are not an optimal choice.   ...

Gene Transfer into Older Chicken Embryos by ex ovo Electroporation

The chicken embryo provides an excellent model system for studying gene function and regulation during embryonic development. In ovo electroporation is a powerful method to over-express exogenous genes or down-regulate endogenous genes in vivo in chicken embryos1. Different structures such as DNA plasmids encoding genes2-4, small interfering RNA (siRNA) plasmids5, small synthetic RNA oligos6, and morpholino antisense oligonucleotides7 can be easily transfected into chicken embryos by electroporation. However, the application of in ovo electroporation is limited to embryos at early incubation stages (younger than stage HH20 - according to Hamburg and Hamilton)8 and there are some disadvantages for its application in embryos at later stages (older than stage HH22 - approximately 3.5 days of development). For example, the vitelline membrane at later stages is usually stuck to the shall membrane and opening a window in the shell causes rupture of the vessels, resulting in death of the embryos; older embryos are covered by vitelline and allantoic vessels, where it is difficult to access and manipulate the embryos; older embryos move vigorously and is difficult to control the orientation through a relatively small window in the shell.
In this protocol we demonstrate an ex ovo electroporation method for gene transfer into chicken embryos at late stages (older than stage HH22). For ex ovo electroporation, embryos are cultured in Petri dishes9 and the vitelline and allantoic vessels are widely spread. Under these conditions, the older chicken embryos are easily accessed and manipulated. Therefore, this method overcomes the disadvantages of in ovo electroporation applied to the older chicken embryos. Using this method, plasmids can be easily transfected into different parts of the older chicken embryos10-12.

Gene Transfer into Older Chicken Embryos by ex ovo Electroporation

A method of gene transfer into chicken embryos at later incubation stages (older than Hamburger and Hamilton stage (HH) 22) is described. This method overcomes disadvantages of in ovo electroporation applied to older chicken embryos and is a useful technique to study gene function and regulation at older developmental stages.

The chicken embryo provides an  excellent model system for studying gene function and regulation during  embryonic development. In ovo electroporation is ...

Mouse Embryonic Development in a Serum-free Whole Embryo Culture System

Mid-gestation stage mouse embryos were cultured utilizing a serum-free culture medium prepared from commercially available stem cell media supplements in an oxygenated rolling bottle culture system. Mouse embryos at E10.5 were carefully isolated from the uterus with intact yolk sac and in a process involving precise surgical maneuver the embryos were gently exteriorized from the yolk sac while maintaining the vascular continuity of the embryo with the yolk sac. Compared to embryos prepared with intact yolk sac or with the yolk sac removed, these embryos exhibited superior survival rate and developmental progression when cultured under similar conditions. We show that these mouse embryos, when cultured in a defined medium in an atmosphere of 95% O2 / 5% CO2 in a rolling bottle culture apparatus at 37 &#176;&#8203;C for 16-40 hr, exhibit morphological growth and development comparable to the embryos developing in utero. We believe this method will be useful for investigators needing to utilize whole embryo culture to study signaling interactions important in embryonic organogenesis.

Serum utilized in embryo cultures contains unknown components that can affect the outcome of experiments especially in studies involving signaling interactions. Here we utilized a serum-free oxygenated culture system and show that mid-gestation mouse embryos cultured for 16-40 hr&#160;exhibit morphological development comparable to embryos developing in utero.

Mid-gestation stage mouse embryos were cultured utilizing a serum-free culture medium prepared from commercially available stem cell media supplements in ...

An Ex vivo Culture System to Study Thyroid Development

The thyroid is a bilobated endocrine gland localized at the base of the neck, producing the thyroid hormones T3, T4, and calcitonin. T3 and T4 are produced by differentiated thyrocytes, organized in closed spheres called follicles, while calcitonin is synthesized by C-cells, interspersed in between the follicles and a dense network of blood capillaries. Although adult thyroid architecture and functions have been extensively described and studied, the formation of the &#8220;angio-follicular&#8221; units, the distribution of C-cells in the parenchyma and the paracrine communications between epithelial and endothelial cells is far from being understood.
This method describes the sequential steps of mouse embryonic thyroid anlagen dissection and its culture on semiporous filters or on microscopy plastic slides. Within a period of four days, this culture system faithfully recapitulates in vivo thyroid development. Indeed, (i) bilobation of the organ occurs (for e12.5 explants), (ii) thyrocytes precursors organize into follicles and polarize, (iii) thyrocytes and C-cells differentiate, and (iv) endothelial cells present in the microdissected tissue proliferate, migrate into the thyroid lobes, and closely associate with the epithelial cells, as they do in vivo.
Thyroid tissues can be obtained from wild type, knockout or fluorescent transgenic embryos. Moreover, explants culture can be manipulated by addition of inhibitors, blocking antibodies, growth factors, or even cells or conditioned medium. Ex vivo development can be analyzed in real-time, or at any time of the culture by immunostaining and RT-qPCR.
In conclusion, thyroid explant culture combined with downstream whole-mount or on sections imaging and gene expression profiling provides a powerful system for manipulating and studying morphogenetic and differentiation events of thyroid organogenesis.

An Ex vivo Culture System to Study Thyroid Development

This protocol describes dissection of mouse embryonic thyroid anlagen and the culture of explants on semiporous filters or on microscopy plastic slides. This system is ideal to study morphogenetic or differentiation events occurring during thyroid development of wild type or knockout embryos, and is amenable to gain- and loss-of-function experiments.

The thyroid is a bilobated endocrine gland localized at the base of the neck, producing the thyroid hormones T3, T4, and calcitonin. T3 and T4 are ...

Preparation of Rat Serum Suitable for Mammalian Whole Embryo Culture

Mammalian whole embryo culture (WEC) is a widely used technique for examining pharmacological toxicity in developing mouse and rat embryos and for investigating the mechanisms of developmental processes. Immediately centrifuged (IC) rat serum is commonly used for WEC and is essential for the growth and development of cultured mouse and rat embryos ex vivo. For the culture of midgestation embryos (i.e., E8.0-12.5 for the mouse, and E10.0-14.5 for the rat), 100% rat serum is the best media for supporting the growth of the embryo ex vivo. To prepare rat serum suitable for WEC, the collected blood should be centrifuged immediately to separate the blood cells from the plasma fraction. After centrifugation, the fibrin clot forms in the upper layer; this clot should be squeezed gently using a pair of sterile forceps and subsequently centrifuged to completely separate the blood cells from the serum. In this video article, we demonstrate our standard protocol for the preparation of optimal IC rat serum, including blood collection from the abdominal aorta of male rats and extraction of the serum by centrifugation.

Mammalian whole embryo culture (WEC) is widely used in teratology and developmental biology. Immediately centrifuged rat serum is commonly provided as a medium for both mouse and rat WEC. In this video, we demonstrate our standard protocol for the preparation of high-quality rat serum suitable for mammalian WEC.

Mammalian whole embryo culture (WEC) is a widely used technique for examining pharmacological toxicity in developing mouse and rat embryos and for ...

Establishment of an Extracellular Acidic pH Culture System

Conditions of the tumor microenvironment, such as hypoxia or nutrient starvation, play critical roles in cancer progression and malignancy. However, the role of acidic extracellular pH in tumor aggressiveness and its underlying mechanism has not been extensively studied compared to hypoxic or nutrient starvation conditions. In addition, a well-defined culture method to mimic the acidic extracellular tumor microenvironment has not been fully reported.
Here we present a simple in vitro culture method to maintain acidic extracellular pH using reduced bicarbonate and increased lactate or HCl concentrations in the culture medium. The medium pH was sustained for at least 24 h and gradually decreased by 72 h following culture of PANC-1 and AsPC-1 pancreatic cancer cells. Three distinct acidic media conditions in this study highly upregulated pH-responsive genes such as MSMO1, INSIG1, and IDI1 compared to hypoxia or nutrient starvation. The upregulation of these genes can be used as a marker of acidic pH. These simple techniques are beneficial to elucidate underlying mechanisms of tumor malignancy under acidic tumor microenvironment. Therefore, our extracellular acidic pH culture system enables discovery of cellular acidic pH responses not only in cancer cells but also in primary cells, such as renal tubular cells, in relation to the other acidic disorders including, diabetic ketoacidosis, lactic acidosis, renal tubular acidosis, and respiratory acidosis.

The acidic tumor microenvironment plays critical roles in tumor progression. To assess the effects of acidic extracellular pH on cancer cells in vitro, we established simple acidic culture systems.

Conditions of the tumor microenvironment, such as hypoxia or nutrient starvation, play critical roles in cancer progression and malignancy. However, the ...