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Why is our (human) early development comprised of the formation of two flat layers of cells?
I'm reviewing for a zoology final and this question came up but I don't know what two layers its even discussing... is it the animal pole & the vegetal pole? You don't even have to fully answer the question if you don't want to, I just want to know what two layers the question is referring to.
That's what I thought of first too, but like you said there are 3. I think my professor wants us to know the whys because we also covered evolution this semester and there's probably an evolutionary advantage to having two flat layers of cells.
2 Answers
- 1 decade agoFavorite Answer
I would think this is referring to the Hypoblast and the Epiblast, the two flat layers of cells in the second week of embryonic development.
Beginning with these two layers, all the subsequent germ layers will be formed. These layers will advance, and allow for all the various tissues and organs to be formed and placed in the correct location. With one layer, it might not be possible to get the correct folding and invaginating to put precursors to all the internal organs in the correct places.
Source(s): Human A&P teacher - Anonymous1 decade ago
sounds like the embryonic germ layers...but there are 3 of those (endo, meso, ecto- derms)...but as to why...only god knows...don't worry about why's in science...focus on how....
a 2 layered embryo is called the inner cell mass...hope this helps