During this process in Xenopus laevis, apical constriction of bottle cells leads to the formation of the dorsal lip of the (*) blastopore.
During this process in birds and mammals, the inward movement of Koller's sickle beyond the posterior marginal zone results in the formation of a structure whose anterior end is known as Hensen's node. A group of cells responsible for mediating this process in zebrafish develop into Kupffer's vesicle. During this process in Xenopus laevis, apical constriction of bottle cells leads to the formation of the dorsal lip of the (*) blastopore. Epiboly, ingression, and convergent extension are common forms of cellular movement that occur during this process. Secondary invagination in this process involves the elongation of the archenteron until it attaches to the animal pole. For 10 points, name this process in which the three germ layers develop from a blastula. 
During this process in birds and mammals, the inward movement of Koller's sickle beyond the posterior marginal zone results in the formation of a structure whose anterior end is known as Hensen's node.
gastrulation 