See also: Segmentation

The egg fertilized undergoes a segmentation in cell S not differentiated, which little by little is organized. This segmentation can divide all the embryonic germ (as at the Amphibians): holoblastic division; or only one part (as at the birds): meroblastic division. The cells thus formed are called blastomères. At some junction S, Annélide S and Arthropod S, the body is organized in segments of comparable organization (Métamérie), thus leading to a segmentation often visible with the eye, after which the cells migrate to give rise to the bodies starting from the embryonic Feuillet. Nowadays, the term of cleavage is employed more and more.

See too

Related articles

• Metamerism
• Embryogenesis

External bond

• Nomenclature of the parts of the body and Metamerism (Segmentation) of the marine planktonique Copepoda