Re: i'm having trouble understanding what the role of epiboly

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