abnormal pharyngeal pouch morphology abnormal third pharyngeal pouch morphology abnormal 3rd pharyngeal pouch morphology MP:0013225 MPheno.ontology abnormal 3rd branchial pouch morphology abnormal third branchial pouch morphology any structural anomaly of the third endodermal branchial pouch located between the third and fourth branchial arches; in mammals, the cranial dorsal aspect of the third pouch generates the inferior parathyroids (or parathyroid III), whereas the caudal ventral part of the pouch gives rise to the thymus epithelium