part_of part of part of develops from inner cell mass bilaminar disc epiblast (generic) inner cell mass derived epiblast NCIT:C34164 embryonic epiblast An embryonic structure that is derived from the inner cell mass and lies above the hypoblast and gives rise to the three primary germ layers. EMAPA:16050 The epiblast cells (appearing on day 8 of human embryonic development) make up a columnar epithelium with dense microvilli on the apical surface. During gastrulation, the epiblast cells undergo epithelial-to-mesenchymal transition and delaminate to become the loose mesenchyme of the primitive streak. The epiblast is present in postimplantation mouse embryos between E5.5-E7.5. EHDAA:42 EHDAA:75 EHDAA2:0000444 UBERON:0008780