Studies on the Hypophysectomized Ferret. X. Growth and Skeletal Development

The relation between the pituitary gland and body growth has been studied by means of hypophysectomy in a number of species of animals. Cushing (1911), from his results with hypophysectomy of the dog, concluded that the gland secreted a substance that controlled and maintained proportionate growth. The results of Smith (1927) and Collip (1934) and his co-workers on the rat show that there is little growth after removal of the pituitary, although the latter authors find that if the rat is hypo-physectomized at an early age (body weight 25-35 g.) it continues to grow until a body weight of 60 g. is reached. The growth stasis following hypophysectomy seems to be characteristic of all mammals. A detailed radiographical study of the effect of hypophysectomy on the development of bone in the rat has recently been made by Mortimer (1937). He finds that the degree of vascularity of the bone is greatly reduced, so that the resorption and deposition of calcium is lessened. Changes in the skeletal system are described as “an osteoporosis simplex with disorganization of the trabecular structure of bone and marrow aplasia”. Special reference is made to the skull, since cranial growth, particularly antero-posterior growth, is greatly retarded by hypophysectomy.