life cycle stage gastrula stage A stage defined by complex and coordinated series of cellular movements that occurs at the end of cleavage during embryonic development of most animals. The details of gastrulation vary from species to species, but usually result in the formation of the three primary germ layers, ectoderm, mesoderm and endoderm. BILS:0000109 BilaDO:0000008 EFO:0001296 FBdv:00005317 HsapDv:0000010 MmusDv:0000013 OGES:000004 OGES:000019 UBERON:0000109 WBls:0000010 XAO:1000005 ZFS:0000047 blastocystis trilaminaris stage trilaminar blastocyst stage trilaminar blastoderm stage trilaminar disk stage trilaminar germ stage trilaminar stage uberon