- Cleavage (embryology) by Shawn Powers
... the subsequent events of blastulation, gastrulation, and interaction that are involved in formation of tissues and organs. Sooner or later, cleavage segregates different cytoplasmic areas into different blastomeres, thus subdividing the substance of the egg qualitatively. These qualitative cytoplasmic differences among blastomeres are then sufficient to account for ...
- Gastrulation by Ella Hicks
The formation of the primordial gut, the archenteron, or digestive cavity of an early animal...
- Protostomia by Great Soviet Encyclopedia
... anal opening emerges from the posterior part of the body. There is an exoskeleton of cuticle, chitin, or shell. The foregut and hindgut develop by invagination of the ectoderm. Blastulation is spiral unless it has undergone a secondary change.
- Cell differentiation by Haley Warner
... tissue from the mesoderm. See Blastulation, Cell cycle, Cleavage (embryology), Embryogenesis, GastrulationThe stable differentiated state is a consequence of multicellularity. A complex organism maintains its characteristic form and identity because populations of specialized cell types remain assembled in a certain pattern. Thus several kinds of cells make up a tissue ...
- Blastulation by Mitchell Chambers
... - or eight-cell stage. Thus blastulation is initiated during early cleavage stages, and formation of the definitive blastula is thought to terminate cleavage and to initiate gastrulation. Initially the diameter of the blastula is no greater than that of the activated egg; subsequently it increases. See GastrulationThe blastula is usually a hollow sphere. Its wall may ...