Calcitonin-biochemistry and physiology.

Abstract

Calcitonin is still a mysterious protein hormone. Secreted by the C-cell in ultimobranchial body or thyroid glands, it seems to act as a hypocalcemic antagonist against parathyroid hormone by inhibiting osteolysis. This concept which was developed especially in small mammals like the rat, does not entirely fit the results gained from other species: in fish, CT levels change in connection with the reproductive cycle in the female, in amphibians, buffering capacity of the organism is bound to the ultimobranchial body, and in birds, sexual development in the male is accompanied by increasing calcitonin levels.