Where is Parathyroid hormone and Calcitonin each synthesize, and by what specific type of cell?

Parathyroid hormone (PTH) and Calcitonin are both hormones involved in regulating calcium levels in the body, but they are synthesized and secreted by different glands and cell types.

1. Parathyroid Hormone (PTH):
PTH is synthesized in the parathyroid glands, which are small endocrine glands located in the neck, usually behind the thyroid gland. The specific type of cell responsible for PTH synthesis is called the chief cell or principal cell. These cells are found in clusters within the parathyroid glands.

2. Calcitonin:
Calcitonin is synthesized in the C-cells (also known as parafollicular cells) of the thyroid gland. These C-cells are distinct from the follicular cells of the thyroid that are responsible for synthesizing thyroid hormones (such as thyroxine or T4). The C-cells of the thyroid gland are scattered between the follicles and secrete calcitonin in response to high levels of calcium in the blood.

In summary, Parathyroid hormone (PTH) is synthesized in the chief cells of the parathyroid glands, while Calcitonin is synthesized in the C-cells of the thyroid gland.