Animated Gif Confocal images showing amphibian gastrulation. The blastopore starts to form at the 5 o'clock position and the archenteron elongates during gastrulation towards the future mouth opening at the 9 o'clock position (No movement? Click Reload/Refresh)

G.I. Tract Several hours after the initial gastrulation movements that form the archenteron (shown above), the gastro-intestinal tract starts to differentiate into 3 major regions, the Foregut, Midgut and Hindgut. The caudal portion of the oral cavity, the pharynx and the liver are offshoots from the forgut endoderm.