An embryo on stage after the blastula, comprising a hollow, two-layered sac of ectoderm and endoderm surrounding an archenteron that communicates using the exterior through blastopore.
A stage in growth of embryos on most animals composed of a two-layered sac of ectoderm and endoderm.
An embryonic kind having its beginning in invagination or pressing in for the wall surface associated with the planula or blastula (the blastosphere) using one side, this provides you with rise to a double-walled sac, with one orifice or mouth (the blastopore) which leads to the hole (the archenteron) lined because of the internal wall (the hypoblast). See Illust. under invagination. In a more basic sense, an ideal stage in embryonic development. See gastræa.
In embryology, that kind of the germ of this Metazoa that is a germcup that the walls consist of two layers.
it will be the consequence of that procedure of invagination which takes place in many creatures, whereby a vesicular morula, blasto-sphere, or blastula is converted into a cup-like two-layered germ, with a blastopore or orifice of invagination, and an endoderm or membrane inclosing a primitive intestinal cavity, the endoderm it self being inclosed within an ectoderm. The word goes into into numerous free compounds of obvious definition, as gastrula-body, -cup, -form, -formation, -germ, -mouth, -stage, -stomach, etc., mostly derived from the translation regarding the German substances used in Haeckel's works. See gastrulation.
double-walled stage regarding the embryo caused by invagination of this blastula; the exterior level of cells could be the ectoderm therefore the inner layer differentiates to the mesoderm and endoderm