|MadSci Network: Development|
Greetings, Wow, I've never heard a question about epiboly asked with such urgency; I can only imagine this relates to a take-home exam or something. Regardless, the answer to your question depends on the model system you're talking about (e.g., zebrafish, chicken embryos, mollusk or the african clawed frog, Xenopus laevis). An average undergrad class is probably just looking to know that you understand how the "germ layers" (ectoderm, mesoderm and endoderm) are formed in one system or another. In my favorite example, the baby slipper snail (Crepidula), "the ectoderm undergoes epiboly from the animal pole and envelops the other cells of the embryo." (Developmental Biology, 6th ed. by Scott Gilbert). In this model, epiboly is the cell movement that brings ectodermal cells from one part of the embryo (the 'animal pole') to another part (the 'vegetal pole' (endoderm)). Epiboly of the ectoderm facilitates new molecular interactions between different cell types. These new molecular interactions are responsible for differentiation of mesodermal cells. Good luck, Chris Reigstad MadSci
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