ABSTRACT
The endocrine function of the gonads and adrenals was studied in mice with congenital athymia (mutation nude); in normal mice thymectomized at 3 days of age and in congenitally athymic mice with thymic transplants from the 5th day of life. The data demonstrated that abnormal function of the adrenals and testes in nude mice is related to the absence of a functionally active thymus during early ontogenesis. The effect of thymosin (fraction 5) on the formation of adrenal functional activity was studied in congenitally athymic and normal mice. Treatment with thymosin during the first days of life resulted in suppressed adrenal function in adult athymic and normal mice. When given to adult normal mice, thymosin also decreased adrenal function. It is suggested that the thymus and its hormone thymosine are of importance in the formation of endocrine functions during the postnatal period in mice.