ABSTRACT
The gastrointestinal tract comprises all components from mouth to anus. In the fourth week of gestation the primitive yolk sac divides into the primitive gut and yolk sac. These are in continuity until the seventh week when the vitelline duct is obliterated. The gut comes from the dorsal aspect of the yolk sac. The primitive gut has three parts: foregut, midgut and hindgut.
