Primitive streak shortens and move towards caudal region and gastrulation almost completed.

Dark peripheral area opaca and central transparent pellucida are distinctly visible.

The process of neurulation begins. The neurectoderm give rise to neural fold and neural groove. Fusion of neural folds begins.

Notochord is now a definite rod it extends into mesoderm as a slender process called head process.

Development of head fold and sub cephalic pocket takes place. Formation of blood islands. Area vasculosa and area vitellina are formed and start to differentiate.