When formed it has differentiated into three layers of geminal cells which later develop into organs.  
It's preceded by a ball of epithelial cells from which, in humans, cells migrate along the primitive streak to produce the archenteron, or primitive gut cavity.  When formed it has differentiated into three layers of geminal cells which later develop into organs.  With a typical cup-like shape, for ten points, what embryonic form follows the blastula and is named for the development of the digestive system.
It's preceded by a ball of epithelial cells from which, in humans, cells migrate along the primitive streak to produce the archenteron, or primitive gut cavity.  
gastrula (accept gastrulation)