Brown adipose tissue proteins impede thymus development in rats

The biological effect of the protein component of hypertrophic brown dispose tissue (BAT) of ground squirrels on thymus development in immature Wistar rats was studied morphologically. It was established that repeated intraperitoneal injections of BAT proteins produced remarkable regression and hypotrophy in the thymus parenchyma. This was demonstrated anatomically and histologically by a decrease in the weight of the thymus treated rats as well as as in the size of the cortical areas of lobules and an expansion of their medulla; also by the thinning away or disappearance of the superficial cortex, a decrease in the number of blasts and immature forms of lymphocytes in mitosis, but an intensification of phagocytosis.