Primitive streak

Definition

The primitive streak is a structure that forms on the surface of the early embryonic disk, marking the beginning of gastrulation, the process where the three primary germ layers develop. It serves as an organizer for cell movement and differentiation during early embryonic development.

Related terms

Gastrulation:

The phase of embryonic development that follows formation of the primitive streak, during which cells migrate to form three primary germ layers (ectoderm, mesoderm, and endoderm).

Germ Layers:

The three layers of cells (ectoderm, mesoderm, and endoderm) formed during gastrulation that give rise to all tissues and organs of an organism.

Embryonic Disk: A flat circular layer of cells in early embryonic development from which the embryo begins to take shape following processes like formation of the primitive streak