embryonic diskThe early embryo before the formation of somites. The embryonic disk is a flat disk of tissue bounded dorsally by the amniotic cavity and ventrally by the yolk sac. The formation of the primitive streak and archenteron in the embryonic disk determines the orientation of the embryo, which then become progressively elongated. Related category• DEVELOPMENTAL BIOLOGYAlso on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History |