Anterior neural tube forms brain. Neural tube overlying the notochord will become the spinal cord. Mesoderm in dorsal paraxial position gives rise to the somites - paired blocks of mesoderm. Notochord, neural tube and somites will continue to form from this region. 1 day to organogenesis.
Cleavage is confined to animal pole.
Blastomeres sit on top of yolk. Figure 2.27 and 2.28 Blastomeres spread over the embryo by epiboly to cover the yolk cell. These cells move toward the dorsal side and converge toward the midline of the embryo. Epiboly occur all around the circumference as does involution - unlike Xenopus.