Branchial pouch

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Pharyngeal or branchial pouches form on the endodermal side between the branchial arches, and pharyngeal grooves (or clefts) form from the lateral ectodermal surface of the neck region to separate the arches. The pouches line up with the clefts, and these thin segments become gills in fish.

[edit] First pouch

This is the only pouch in which the endoderm and ectoderm remain close together, as the tympanic membrane. There is minimal mesoderm in the tympanic membrane.

• The endoderm lines the future auditory tube, middle ear, mastoid antrum, and inner layer of the tympanic membrane.
• The ectoderm lines the future external acoustic meatus and outer layer of the tympanic membrane.
• Mesoderm remains as the middle portion of the tympanic membrane, where the endoderm of the first pharyngeal pouch and the ectoderm of the first pharyngeal cleft have met.

[edit] Second pouch

• Contributes to the middle ear, tonsils, supplied by the glossopharyngeal nerve.

[edit] Third pouch

• Derivatives include the inferior parathyroid glands and thymus

[edit] Fourth pouch

• Derivatives include the superior parathyroid gland and parafollicular C-Cells of the thyroid gland.

[edit] Fifth pouch

• Rudimentary structure, becomes part of the fourth pouch.

[edit] See also

• branchial arch
• DiGeorge syndrome

[edit] External links

• Swiss embryology (from UL, UB, and UF) rrespiratory/korperhohlen01 (Item #1 at Fig. 14)
• ‹ The template below has been proposed for deletion. See templates for deletion to help reach a consensus on what to do. ›

Embryology at Temple parch98/ARCHII97/sld017

• Outline at howard.edu (scroll down to "III. THE PHARYNGEAL POUCHES")