Anatomy of the Parathyroid Glands

The parathyroid glands are usually embedded in the posterior part of each lobe of the thyroid gland. There are usually four parathyroid glands. Their cells are organized in densely packed masses or cords rather than in follicles.
The parathyroid glands secrete parathyroid hormone (PTH), which is important in the regulation of calcium levels in body fluids. Bone, the kidneys, and the intestine are its major target tissues. Without functional parathyroid glands, the ability to regulate blood calcium levels adequately is lost.