Parathyroid

The parathyroid glands are located on the posterior aspect of the thyroid. There may be anywhere from 2 to 6 glands in an individual. Cells in these glands secrete parathyroid hormone, which acts to increase calcium resorption from bone and in the renal tubules. It also acts to increase the synthesis of the active form of Vitamin D. Vitamin D, in turn, increases the absorption of Ca++ from the small intestine.

#79 Parathyroid, H&E

The majority of the cells with small centrally placed round nuclei and clear cytoplasm are chief cells. These produce parathyroid hormone. Large intensely eosinophilic oxyphil cells may be found interspersed or in nests among the chief cells. The function of the oxyphil cell is unknown. Review the typical endocrine arrangement of anastomosing cords of cells surrounded by sinusoidal capillaries.