Growth and involution of lymphatic tissue and their relation to secretions of the adrenal cortex in CBA mice

The primary aims of these experiments were: (1) to determine the responses of various representative lymphatic organs to the process of aging in intact animals, (2) to determine the responses of the various lymphatic organs to adrenalectomy at successive ages. From the data obtained it was hoped to secure information on the role of the adrenal glands in the control of growth and involution of each of the lymphatic organs. Studies were made of the normal body growth and of the changes in absolute and relative weights of lymphatic and certain non-lymphatic organs from prepuberty, through puberty and sexual maturity to senility in male and female mice of the CBA strain. These studies of the effect of adrenalectomy on the growth and involution of the lymphatic organs have shown that: 1. The secretions of the adrenal glands, probably the cortex, restrain growth and enhance involution. 2. The influence of the adrenal glands is greatest in the youngest animals and in the oldest animals, indicating greater secretory activities of these glands during those periods of life. 3. The lack of the secretions of the adrenal glands, however, does not permit unlimited growth. The increased growth following adrenalectomy is greatest after a five day period. 4. The different lymphatic organs respond differently to adrenalectomy, although all except the thymus following the same general pattern. The effects on the thymus are, in general, the reverse of those of other organs. 5. Each lymph organ responds differently at different ages. In all but the thymus the response tends to be greatest in the young animals and senile animals, and least in the sexually mature animals. The response of the thymus tends to be greatest in the sexually mature animals. 6. There exist sex differences in the response of all lymphatic organs to adrenalectomy at all ages. There are small and more quantitative in nature and are most evident in young animals. These sex differences indicate a role played by sex hormones in controlling growth and involution of lymphatic tissue. 7. The weights of the adrenal glands were greater in the females at all ages and this may be correlated with the greater relative weights of lymphatic organs of the females. 8. These variations among glands and in age, sex, and period following adrenalectomy must be recognized in comparing data obtained from the literature and in future experiments.