Abstract
Young adult male albino rats were exposed to 600 r of total-body X-irradiation and the occurrence of plasma cells was studied on sections made from thymus, mesenteric lymph nodes and spleen. One to 30 days after irradiation, the marked increase in percentage of plasma cells has occurred, reaching its peak during the period of three to 10 days, decreasing in number gradually thereafter. In a quantitative estimation of plasma cell on the 10th day after irradiation, by means of cell counting method used in thymolymphatic tissues (Awaya,1962) and of differential cell counts in imprint, there was found an absolute increase of these cells in all organs with the exception of thymus in spite of a marked decrease of total number of nucleated cells.
