Parafollikelcellen

Parafollikelcellen, also known as C cells, are endocrine cells found in the thyroid gland of mammals. They are located in the interstitial tissue between the thyroid follicles. These cells are distinct from the follicular cells that produce thyroid hormones T3 and T4. Parafollikelcellen are responsible for the synthesis and secretion of calcitonin. Calcitonin is a hormone that plays a role in calcium and phosphate homeostasis, primarily by inhibiting osteoclast activity, which are cells that break down bone. This action leads to a decrease in blood calcium levels. The secretion of calcitonin is stimulated by high levels of calcium in the blood. While their function is well-established in many species, the precise physiological significance of calcitonin in humans is still a subject of ongoing research, as its role in normal calcium regulation appears to be less prominent compared to parathyroid hormone. Parafollikelcellen are derived from the ultimobranchial bodies during embryonic development.