What are each germ layer’s derivatives? Which are dorsal and which are ventral derivates? Endoderm Epithelial lining of respiratory tract and GI tract. Mesoderm There are dorsal/ventral differences in what the mesoderm gives rise to. This is induced by differences in dorsal and ventral endoderm. Organizer cells self-diffrentiate into dorsal mesoderm (notochord), organizer cells dorsalize [...]

Invagination, involution, ingression and convergent extension are the types of cell movement during gastrulation. Invagination and involution maintain epithelium. In amphibians, the dorsal lip of the blastopore invaginates, involutes and then spreads out between the ectoderm and endoderm to form the mesoderm. Sea urchin embryos invaginate to form mesoderm. Birds and mammals’ blastodisc ingresses at [...]

The end result of gastrulation is the transformation of the blastula, which consists of a ball or disc of relatively undifferentiated cells into an embryo that contains three germ layers. The mode of gastrulation depends on the distribution of yolk, but all different types of gastrulation are related to each other in that they are [...]