abnormal embryonic tissue morphology abnormal gastrula morphology 2014-06-26T15:11:51Z MP:3000001 MPheno.ontology abnormal trilaminar blastocyst morphology abnormal trilaminar disc morphology abnormal trilaminar embryonic disc morphology abnormal trilaminar embryonic disk morphology abnormal trilaminar germ disc morphology abnormal trilaminar germ disk morphology any structural anomaly of the pear shaped trilaminar embryonic stage in which the primititve streak elongates, the epiblast cells migrate medially towards the streak, enter the primitive groove and migrate laterally to organize into the intraembryonic mesoderm (epithelio-mesenchymal transition) between the embryonic ectoderm and primitive endoderm; the notochordal process forms and extends, and the disc becomes pear shaped as the notochordal process grows cynthia.smith