part_of part of preceded_by is preceded by preceded by embryo stage part embryo stage cleavage stage blastula stage An early stage of embryonic development in animals. It is produced by cleavage of a fertilized ovum and consists of a spherical layer of around 128 cells surrounding a central fluid-filled cavity called the blastocoel. The blastula follows the morula and precedes the gastrula in the developmental sequence. BILS:0000108 BilaDO:0000007 EFO:0001282 HsapDv:0000006 MmusDv:0000007 OGES:000003 OGES:000016 OGES:000021 OpenCyc:Mx4rEetFnKP2EdqAAAACs4vPlg UBERON:0000108 WBls:0000005 XAO:1000003 ZFS:0000045 consider adding a preceding stage 'morula stage' as part of cleavage uberon