THE ADRENAL GLAND IN LIZARDS AND SNAKES

Abstract

SUMMARY The anatomy and histology of the adrenal glands of the West African lizard (Agama agama L.) and of the common grass snake (Natrix natrix L.) are described. In lizards, 30 days after hypophysectomy, there was considerable degeneration, with a 60% loss in weight, of the adrenal. The chromaffin cells underwent no histological change. Some cortical cells contained large sudanophilic, Schultz-positive lipid droplets, some nuclei remaining normal, others showing intense basophilia and shrinkage. In other cells, the cytoplasm was reduced to a small acidophilic patch, with pyknotic nuclei. The sodium and potassium contents of the blood and muscle of these hypophysectomized animals were within the normal range. In snakes, the successive histological stages in the degeneration of the adrenal cortex 9–11, 20 and 30–39 days after hypophysectomy are described. Injection of mammalian ACTH allowed the adrenal to maintain a normal histological appearance in hypophysectomized snakes. In addition, these animals, and normal animals similarly injected, showed degenerative areas in the cortex, attributable to over-stimulation. Injections of cortisone and DCA into unoperated animals were followed by degeneration of the adrenal cortex. After unilateral adrenalectomy, the contralateral adrenal was hypertrophic. The sodium and potassium contents of blood and muscle, together with the water content of the latter, were obtained in all groups of animals. Despite the histological changes induced in the adrenal cortex by the various experimental procedures, there were no profound changes in the distribution of salt-electrolytes in any of the animals. The sodium content of muscle of normal snakes was about twice the value found in vertebrate muscle in general. The results are discussed in the light of present-day knowledge of the adrenal cortex in vertebrates, especially of the gland in mammals.