abnormal embryonic tissue morphology abnormal pharyngeal groove morphology MP:0013231 MPheno.ontology abnormal branchial cleft morphology abnormal branchial groove morphology abnormal pharyngeal cleft morphology any structural anomaly of the ectodermally lined depressions (grooves or clefts) that separate the branchial arches externally on each side; only the first of the four pairs of branchial grooves persists in the adult to form the epithelium of the external auditory meatus and part of the tympanic membrane; the second, third, and fourth grooves are overlapped by the development of branchial arch 2 and form a slit-like depression known as the cervical sinus which is ultimately obliterated by the fusion of its walls during extension of the cervical flexure