abnormal embryonic tissue physiology abnormal preimplantation embryo development failure of morula compaction 2013-09-26T15:58:08Z MP:0012111 MPheno.ontology csmith inability to initiate or maintain the first cell differentiation event in mammalian development, occurring at the late eight-cell stage in the mouse, whereby cells on the outer part of the morula become flattened and bound tightly together with the formation of desmosomes and gap junctions, becoming nearly indistinguishable