Primitive groove - AbsoluteAstronomy.com

A shallow groove, the primitive groove, appears on the surface of the primitive streak

Primitive streak

The primitive streak is a structure that forms during the early stages of avian, reptilian and mammalian embryonic development.-Introduction:...

, and the anterior end of this groove communicates by means of an aperture, the blastophore, with the yolk-sac.

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.