What is parafollicular cells?

Parafollicular cells, also known as C cells, are a type of endocrine cell located in the thyroid gland. They are located in the spaces between thyroid follicles and are responsible for producing and secreting the hormone calcitonin. Calcitonin plays an important role in regulating calcium metabolism by reducing the amount of calcium released from bones and increasing the amount of calcium excreted in urine, thus lowering blood calcium levels. Parafollicular cells are derived from neural crest cells and can be distinguished from follicular cells by their clear cytoplasm and lack of colloid production. The function of parafollicular cells is tightly regulated by calcitonin gene-related peptide (CGRP), which acts as a modulator of calcitonin secretion. In addition to calcitonin, parafollicular cells also produce a number of other peptides, including chromogranin A, which may have paracrine or autocrine functions in the thyroid gland and elsewhere in the body. Dysregulation of parafollicular cell function and calcitonin secretion has been implicated in a number of endocrine disorders, including medullary thyroid carcinoma and primary hyperparathyroidism.