Paradoxical Resistance of Thymus Lymphocytes to High Doses of X-Radiation

Abstract

Rats were exposed to various doses of X-rays and 5 hours later the percentage of dead (pyknotic) lymphocytes in the various lymphoid organs was determined. The lymphocytes of the spleen, the thymus (up to 5000r), and six different lymph nodes were equally sensitive to radiation, but those of Peyer''s patches were more sensitive than these. The response of the thymus was paradoxical in that after very high doses fewer lymphocytes became pyknotic than after lower doses. It was shown that the failure of thymus lymphocytes to become pyknotic after high doses of radiation was not due to "fixation" or the inactivation of autolytic enzymes.