part of part of has part has part in taxon develops from develops from existence starts and ends during Theria <mammals> morula inner cell mass trophoblast blastula stage blastula blastocyst https://upload.wikimedia.org/wikipedia/commons/7/72/Blastocyst_English.svg SCTID:308837009 Wikipedia:Blastocyst EMAPA:36035 MESH:D001755 UBERON:0000358 BTO:0001099 The mammalian blastocyst is a hollow ball of cells containing two cell types, the inner cell mass and the trophectoderm[GO]. EFO:0000295 NCIT:C13739 GAID:1153 blastocystis FMA:83041 Gilbert fig11.32 has blastocyst has giving rise to ICM and trophoblast (which in this source is a synonym for trophectoderm) blastula EV:0100394 CALOHA:TS-0076 UMLS:C1281743 uberon embryonic structure