|Section through embryonic disk of Vespertilio murinus.|
|Surface view of embryo of a rabbit. (After Kölliker.) arg. Embryonic disk. pr. Primitive streak.|
|Gray's||subject #6 47|
The floor of the amniotic cavity is formed by the embryonic disk (or embryonic disc) composed of a layer of prismatic cells, the embryonic ectoderm, derived from the inner cell-mass and lying in apposition with the entoderm.
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