Changes Induced in the Mouse Spleen by Graded Doses of Total-Body X-Irradiation

Albino Carworth Farms # 1 mice of both sexes, 12 to 14 weeks of age, bred in our own laboratory, fed Wayne Lab Blox ad libitum, were placed in perforated plastic tubes without anesthesia for x-irradiation exposure. X-Irradiation was with a 250-kvp therapy machine, 0.5 mm copper and 1.0 mm aluminum filtration. The target-to-mouse distance was 75 cm, and the radiation intensity was 32 r/min with a maximum variation of 5% within the field limits used. Radiation doses of 30, 50, 100, 150, 200, 250, 400, 500, 600, 800, 1000, and 1500 r were administered in a continuous dose. The animals were then returned to their cages and were sacrificed 24 hours later by decapitation with shears without anesthesia. The spleen was removed and weighed, and aliquots were subjected to DNA and acid DNase analyses as previously described (1, 2). Five to ten animals were used at each dose studied, and the results averaged. An equal number of animals, similarly handled, but not irradiated, served as controls for each point.