pharyngeal pouches

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pha·ryn·ge·al pouch·es

paired evaginations of embryonic pharyngeal endoderm, between the pharyngeal arches, extending toward the corresponding ectodermally lined pharyngeal grooves; during development they evolve into epithelial tissues and organs, such as thymus and thyroid glands.

pharyngeal pouches, the four pairs of evaginations from the lateral walls lining the pharynx between the branchial arches in a developing embryo.
References in periodicals archive ?
1-4) The arches are embryologically separated by 4 pharyngeal (or branchial) clefts laterally and 4 pharyngeal pouches medially.
1) The development of many structures in the head and neck is immediately related to either the branchial arches or the pharyngeal pouches.
Older theories hold that they are congenital abnormalities caused by an incomplete obliteration of pharyngeal pouches.
2) The thymus is derived from the third and fourth pharyngeal pouches.