[Development of the adrenal medulla in rats subjected to treatment inducing the Sipple syndrome].

The human Sipple syndrome associates a thyroid-C-cell tumor and a pheochromocytoma. A treatment with the antithyroid drug thiamazole allows obtaining experimentally a similar syndrome in rat. Present paper seeks to analyse changes which happened in the medullary zone of adrenal glands before and during the development of the tumors. During the treatment by thiamazole both adrenal cortex and medulla were atrophied. After the treatment was stopped, the weight of the gland increased, as compared with its previous state, and this was chiefly due to the hyperplasia of medullary cells, from which pheochromocytomas originate. The initial atrophy of adrenal gland depends on the thiamazole-induced hyperthyroidism, but the mechanism of the medullary hyperplasia subsequent to the treatment ending is unknown. It results probably from a secondary hyperthyroidism.