They are called the chief cells. These cells are found in the parathyroid gland. they produce PTH and increase Ca2+ levels. These are small round cells with a central nucleus. PTH is antagonist to calcitonin which reduces Ca in body. Parathyroid glands found on the posterior surface of thyroid gland. There is a superior/inferior one. They are made up of chief and oxyphil cells, the chief cells produces the parathyroid hormone while the oxyphil cells no one knows what they do.
