Parafollicular cells (also called
C cells) are
neuroendocrine cells in the
thyroid which primary function is to secrete
calcitonin. They are located adjacent to the thyroid follicles and reside in the connective tissue. These cells are large and have a pale stain compared with the
follicular cells or colloid. In
teleost and avian species these cells occupy a structure outside the thyroid gland named the
ultimobranchial body.