key term - Cleavage

Definition

Cleavage in embryonic development refers to the series of rapid cell divisions that occur after fertilization, transforming the single-celled zygote into a multicellular structure known as a blastula. These divisions do not increase the size of the embryo but increase the number of cells, partitioning the embryo's volume into smaller, multicellular units.

Related terms

Zygote:

A single cell formed by the fusion of an egg and sperm, marking the beginning of embryonic development.

Blastula: A spherical layer of cells (the blastoderm) surrounding a fluid-filled cavity (the blastocoel) that develops during early embryonic stages following cleavage.

Gastrulation:

The process following cleavage and blastula formation where the embryo reorganizes into a three-layered structure called the gastrula, which will differentiate into various tissues and organs