The role of the parafollicular cell of the thyroid gland in the pathogenesis of congenital osteopetrosis in mice

Congenital osteopetrosis as manifested in the grey‐lethal, microphthalmic and osteosclerotic stocks of the house mouse is characterized by an increased rate of bone matrix formation, hyperplasia of the parafollicular cell population of the thyroid gland and hypocalcemia. Osteopetrotic mice were abnormally resistant to the tendencies of parathyroid extract to promote hypercalcemia and to depress osteogenesis. The results of this investigation suggest that the parafollicular cell is the source of an osteoblast‐stimulating factor and that an excess of this factor results in osteopetrosis.