An ex-ovo Chicken Embryo Culture System Suitable for Imaging and Microsurgery Applications
Summary
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.
Abstract
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.
Protocol
Discussion
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 …
Disclosures
The authors have nothing to disclose.
Materials
| Material Name | Type | Company | Catalogue Number | Comment |
|---|---|---|---|---|
| Fertile white Leghorn chicken eggs | ||||
| Model GB1, Avery Incubators, Hugo CO | ||||
| Saran Wrap | ||||
| Kimwipes | Kimberly-Clark, Inc. | |||
| Rubber bands | ||||
| Warm sterile water | ||||
| 9 oz plastic cup | ||||
| 100 mm diameter Petri dish | ||||
| 1602N thermal air | GQF Manufacturing CO, Savannah GA | |||
| Fluorescein-conjugated dextran (2 MDa, 1% w/v in phosphate buffered saline) | Sigma Aldrich Inc. | |||
| Microforge | Glassworx, Inc, St Louis MO | |||
| Glass capillary tubes (0.75 mm ID) | ||||
| Micromanipulator | World Precision Instruments, Sarasota FL | Model M3301L | ||
| Fluorescent microscopy | Zeiss | Z20 | ||
| Fine 55-forceps | World Precision Instruments, Sarasota FL | |||
| 10-0 nylon surgical suture | Ethicon | |||
| Tubing | VWR | 1mm OD | ||
| 3 mL syringe | BD | |||
| 200 μL pipetter and pipette tips | VWR |
References
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