part of part of has part has part overlaps ectoderm endoderm embryonic structure pharyngeal arch pharyngeal pouch pharyngeal cleft pharyngeal membrane FMA:295758 EMAPA:32749 branchial membrane branchial arch membrane NCIT:C34251 each membrane is initially composed of an inner layer formed by the endodermal lining of a branchial pouch and an outer layer formed by the ectodermal lining of the branchial groove; later, these two layers become separated by a thin layer of mesoderm; only the first branchial membrane contributes to the formation of an adult structure, i.e. the tympanic membrane (aka eardrum); the second, third, and fourth membranes are obliterated[MP] UBERON:0009210 A thin fold of ectoderm and endoderm that separates the pharyngeal pouches from the pharyngeal clefts in a developing embryo. pharyngeal membrane