two pairs of yellowish-brown endocrine gland that are situated behind, or sometimes embedded within, the thyroid gland. They are stimulated to produce parathyroid hormone by a decrease in the amount of calcium in the blood.
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small bodies apposed to the posterior surface of the thyroid gland, developed from the endoderm of the branchial clefts, occurring in a variable number of pairs, commonly two (glandula parathyroidea inferior and glandula parathyroidea superior [TA]) (see inset on Plate 17). The parenchyma comprises masses and cords of epithelial cells, which have been divided into two main types: chief cells and oxyphil cells, but intermediate forms exist. The chief cells secrete parathyroid hormone, a major regulator of calcium and phosphorus metabolism. Called also parathyroids and parathyroid bodies.Medical dictionary. 2011.