A pharyngeal pouch between pharyngeal arch 4 and arch 5 or 6 (a fifth arch never establishes in amniotes).
Comment:
[development-note] "Derivatives include: superior parathyroid glands and ultimobranchial body which forms the parafollicular C-Cells of the thyroid gland. Musculature and cartilage of larynx (along with the sixth pharyngeal pouch)[WP] in most mammals, excluding rodents, the dorsal part of each fourth pouch develops into a superior parathyroid gland (parathyroid IV), which lies on the dorsal surface of the thyroid gland (the parathyroid glands derived from the third pouches descend with the thymus and are carried to a more inferior position than the parathyroid glands that are derived from the fourth pouches); the elongated ventral part of each fourth pouch develops into the ultimopharyngeal body, which fuses with the thyroid gland, giving rise to the calcitonin-producing parafollicular or C-cells of the thyroid gland. In the mouse, but also in the rat and hamster, the dorsal fourth pouch does not generate a parathyroid. Thus, rodents develop only one pair of parathyroid glands." xsd:string {source="MP"}; [homology-note] "A conserved feature of all vertebrate embryos is the presence of a series of bulges on the lateral surface of the head, the pharyngeal arches; it is within these structures that the nerves, muscles and skeletal components of the pharyngeal apparatus are laid down. The pharyngeal arches are separated by endodermal outpocketings, the pharyngeal pouches.[well established][VHOG]" xsd:string {date_retrieved="2012-09-17", external_class="VHOG:0000971", ontology="VHOG", source="DOI:10.1111/j.1469-7580.2005.00472.x Graham A, Okabe M and Quinlan R, The role of the endoderm in the development and evolution of the pharyngeal arches. J Anat (2005)", source="http://bgee.unil.ch/"}