Agnathia and associated malformations in a male rhesus monkey

Background  Agnathia is a rare malformation characterized by the absence of the mandible. Methods  A male rhesus monkey with malformations was found dead and studied by internal examination, radiographs and histopathology. Results  A case of a rare first branchial arch anomaly with agenesis of the mandible and tongue is presented. The animal also had visceral deformities. However, ears were normal in shape and only slightly low in position. The craniofacial malformations may reflect incomplete separation of the first branchial arch into its maxillary and mandibular processes. Conclusions  The association between the craniofacial and other corporal anomalies is unclear.