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Pharyngeal pouches form on the endodermal side between the arches, and pharyngeal grooves (or clefts) form from the lateral ectodermal surface of the neck region to separate the arches. [8] In fish, the pouches line up with the clefts, and these thin segments become gills.
The third pouch possesses dorsal and ventral wings. Derivatives of the dorsal wings include the inferior parathyroid glands, while the ventral wings fuse to form the cytoreticular cells of the thymus. The main nerve supply to the derivatives of this pouch is cranial nerve IX, glossopharyngeal nerve.
However, it is now accepted [who?] that it is the vertebrate pharyngeal pouches and not the neck slits that are homologous to the pharyngeal slits of invertebrate chordates. [citation needed] Pharyngeal arches, pouches, and clefts are, at some stage of life, found in all chordates. One theory of their origin is the fusion of nephridia which ...
Pharyngeal arches are formed during the fourth week. Each arch consists of a mesenchymal tissue covered on the outside by ectoderm and on the inside by epithelium of endodermal origin. In human embryology, there are six arches which are separated by pharyngeal grooves externally and pharyngeal pouches internally.
I-IV pharyngeal arches, 1–4 pharyngeal pouches (inside) and/or pharyngeal grooves (outside) a Tuberculum laterale b Tuberculum impar c Foramen cecum d Ductus thyreoglossus e Sinus cervicalis. The pharyngeal apparatus is an embryological structure. [1] [2] It consists of: pharyngeal grooves (from ectoderm) pharyngeal arches (from mesoderm)
Embryonic pharyngeal slits, which form in many animals when the thin branchial plates separating pharyngeal pouches and pharyngeal grooves perforate, open the pharynx to the outside. Pharyngeal arches appear in all tetrapod embryos: in mammals, the first pharyngeal arch develops into the lower jaw (Meckel's cartilage), the malleus and the stapes.
The human embryo forms five sets of endoderm-lined pharyngeal pouches. The third and fourth pouch are responsible for developing into the inferior and superior parathyroid glands, respectively. [8] The third pharyngeal pouch encounters the developing thyroid gland and they migrate down to the lower poles of the thyroid lobes.
Pharyngeal pouch can refer to: Zenker's diverticulum; Pharyngeal pouch (embryology) This page was last edited on 29 December 2019, at 18:29 (UTC). Text is available ...