abnormal preimplantation embryo development abnormal bilaminar embryonic disc 2013-09-23T14:17:51Z MP:0012103 MPheno.ontology abnormal bilaminar embryonic disk abnormal embryonic disc morphology abnormal embryonic disk morphology abnormal embryonic shield morphology abnormal germinal disc morphology abnormal germinal disk morphology any structural anomaly of the flattened, almost circular bilaminar plate of cells formed when the inner cell mass (aka embryoblast) forms two epithelial layers, each of a distinct lineage, separated by an extracellular basement membrane: the external (dorsal) layer is called the epiblast and the internal (ventral) layer is called the hypoblast (aka primitive endoderm); together, they compose the bilaminar embryonic disc csmith