Management of anomalies of the third and fourth branchial pouches
develop into the middle ear, tonsils, thymus, and parathyroid glands.
The pharyngobranchial region, the part of the animal posterior to the mouth and ventral to the orbits and pectoral fins, is generally not well preserved, and the number of branchial pouches
and branchial openings is uncertain.
The ectoderm, joining the arches, forms the branchial clefts, and the endoderm the branchial pouches