Organ Weight Analysis in Mice Given Fractionated X-Irradiation

Abstract

Female CF-1 mice were given 6 weekly doses of total body X-radiation to accumulated total amounts between 400 and 1200 r. One week after the last treatment they were sacrificed, organs weighed, and the weights corrected for changes in body weight. No relative weight change occurred in kidneys, heart or adrenals; muscle and liver showed a slight relative increase. Thymus, uterus, and ovaries showed an approximately exponential loss of weight with increasing dose. The spleen responded atypically, decreasing at lower dosages and returning to control weight in the range 600-1200 r. Study of spleen sections shows that the white pulp and inactive red pulp behave like the radiosensitive organs (e.g., thymus) while active red pulp (extramedul-lary myelopoiesis) increases with the dosage and accounts for the rising spleen weight at higher dose levels. Studies during the irradiation period show that there are 2 phases of recovery; the thymus behaves similarly but fails to show overcompensation.