The effect of hypophysectomy of the rabbit

Abstract

In recent years the effect of surgically removing the pituitary gland has received considerable attention. two classes of vertebrates, Amphibia and Mammalia, have largely been used in these studies. Practically all the experimental work on ablation in mammals has been done on two species, namely, dogs (Cushing et al., 1910; Aschner, 1912; Houssay, 1931; and many others), and more recently rats (Smith, 1930; and others). Following the epoch-making discovered of Smith and Engle (1926) and Aschheim and Zondek (1927), that implanted pituitary gland will hasten sexual maturity in the rat, a number of workers have been attempting to isolate the hormones from the anterior lobe. It has become increasingly apparent that adequate test animals are necessary for the physiological assay of the various hormone fractions and it is now equally apparent that only with animals whose pituitaries have been removed may purified products be assayed with any certainty. The peculiarities of the rabbits reproductive cycle and also its possible utility for hormone assay, make it unusually interesting for studies on the effect of hypophysectomy, but the inaccessibility of the gland has somewhat retarded work on this species. In conjunction with Dr. L. L. Smith, however, method for ablating the pituitary was recently elaborated (Smith and White, 1931) which left the animals essentially healthy so that they survived for considerable periods. It therefore seemed interesting to determine the extent of the changes caused by hypophysectomy in the rabbit and to attempt substitution therapy with purified hormones. The data on untreated hypophysectomized animals will be presented in the present paper.