Calcitonin is secreted from -

Calcitonin is a hypocalcemic peptide hormone that in several mammalian species acts as an indirect antagonist to the calcemic actions of PTH. Calcitonin is produced by the thyroid medullary C cells, derived from the neural crest derivatives from the ultimobranchial body. The C cells are interspersed throughout the thyroid gland, although their density is greatest in the juncture of the upper one-third and lower two-thirds of the gland. The C-cells are impoant because of their involvement in medullary thyroid cancer. Reference : page 2283 Harrison's Principles of Internal Medicine 19th edition