Embryology, Pharyngeal Pouch

Excerpt

Pharyngeal pouches are endodermal out-pockets occurring between the pharyngeal arches in embryological development. Various transcription factors regulate the mechanical bending of the endodermal tube, resulting in pharyngeal pouch formation. The pouches give rise to tissues responsible for the formation of the middle ear cavity and eustachian tube, palatine tonsils, thymus, parathyroid glands, and parafollicular cells of the thyroid. Malformations in the development of the pharyngeal pouches can cause DiGeorge syndrome, branchio-oto-renal (BOR) syndrome, cyst formation in the neck, and concerns related to the respective structures of individual pouches. Proper pharyngeal pouch formation is essential to individual pharyngeal arch separation and proper organismal development during embryogenesis.