Primary Germ Layers

∞ generated and posted on 2016.08.31 ∞

Initial differentiation seen among diploblastic and triploblastic animals during embryonic development.

The resulting tissue layers minimally consist of the inside or endoderm (i.e., as lining the gut or gastrovascular cavity) and the outside or ectoderm. Found between these two layers in triploblastic animals is the mesoderm, or mesodermal tissue (versus ectodermal or endodermal tissues).

These layers form in the course of what is known as gastrulation, where the the hollow ball of cells known as the blastula invaginates to form the primitive gastric portion of the embryo known as the archenteron (and which is lined by endodermal tissue).