THE EFFECT OF X-IRRADIATION ON THE CELL SIZE DISTRIBUTION OF THYMUS LYMPHOCYTES

Abstract

The effect of X-irradiation on the cell size distribution of thymus lymphocytes was studied with the aid of an electronic Coulter cell counter.In the thymus the small lymphocytes were the most radioresistant and the large lymphocytes were repopulated before the medium-sized lymphocytes. As the radiation dose was increased from 50 to 400 r, there was a decrease in the large to small thymocyte ratio, and a longer time period was required for a return to the normal ratio. Single and repeated doses of X-irradiation produced much the same type of effect on the large to small ratio of both thymus and spleen lymphocytes, and it was concluded that the effects of X-irradiation on the cell size distribution of lymphocytes in the thymus and spleen were similar.