Calcium regulation in reptiles

It is clear from the few studies which have been done that the parathyroid gland is essential for normal calcium and phosphate homeostasis in reptiles. More studies are needed of different species and groups of reptiles, and of the effect of parathyroid hormone upon bone and kidney of these animals. The explanation for the seeming lack of importance of the parathyroid gland in turtle calcium regulation may lie in the large stores of calcium and phosphate in the bony shells of these animals. Experiments to test this hypothesis are yet to be done. The involvement of the ultimobranchial body in calcium metabolism in reptiles is at present a very tenuous hypothesis. Clearly further studies are necessary to determine the function of this gland, which appears ultrastructurally to be an active secretory organ.