Tin concentration in the thymus glands of rats and mice and its relation to the involution of the gland.

Tin is an ubiquitous element and thus enters mammals through the food chain. It has never been found to be dysfunctional in either plants or animal tissue and has been regarded as an innocuous background material. Of the many organs and glands that have been analyzed for tin, only the thymus gland exhibits an above average value for tin. A complete study on the tin content in the thymus gland has never been published and this work is an attempt to investigate this subject. Three types of rodents were used in this study; inbred Lewis rats, inbred A/KI mice (a breast cancer prone mouse) and outbred COBS mice (a cancer resistant mouse). The tin analysis of the muscle, spleen, and thymus indicated constant values for the muscle and spleen tissue, but an increase in the thymic tin concentration (ppm) with age. Besides normal aging studies, the animals were administered the disodium salt of dexamethasone-21-phosphate (dexa), which causes rapid loss of lymphocytes from the spleen and thymus but has no effect upon the muscle. Tin concentration in the muscles remained constant, showed a loss from the spleen and an increase in the thymus gland. The increase indicates that the tin was probably located in the medulla of the thymus, which may be the active biochemical site for tin in rodents. When compared to the COBS mice, the A/KI mice showed a non-statistical difference in tin content in the muscle and spleen and statistically significant lower tin content in the thymus gland.