abnormal digestive system development abnormal buccopharyngeal membrane morphology 2014-01-01T17:21:59Z MP:0012521 MPheno.ontology abnormal oral membrane morphology abnormal oral plate morphology abnormal oropharyngeal membrane morphology abnormal pharyngeal membrane morphology abnormal pharyngeal septum morphology any structural anomaly of the thin bilaminar membrane derived from the prechordal plate that is devoid of mesoderm and formed by the apposition of the stomodeal ectoderm with the foregut endoderm; after the embryonic head fold has evolved it lies at the caudal limit of the stomodeum, forming a septum between the primitive mouth and pharynx; the membrane eventually disappears, and thus a communication is established between the mouth and the future pharynx csmith