CHROMOSOME ABNORMALITIES IN LIVER AND MARROW OF MICE IRRADIATED WITH FAST NEUTRONS, GAMMA-, AND X RAYS. EFFECT OF DOSE RATE.
NAVAL RADIOLOGICAL DEFENSE LAB SAN FRANCISCO CALIF
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Low dose rate irradiation with either gamma-rays or fast neutrons resulted in fewer chromosome abnormalities in liver and bone marrow than did comparable high dose rate irradiation with X rays or neutrons. Neutrons generally produced more aberrations than the low radiations, but a dose rate effect was apparent with both types of radiation. Unstable chromosome aberrations, as well as total aberrations, were reduced in the low dose rate groups, evidence for the action of an intracellular repair process. For both technical and theoretical reasons, the liver and bone marrow are not ideal systems for quantitative studies of the effects of ionizing radiation on mammalian chromosomes. In a few mice, the clonal chromosome changes provided a means of identifying myeloid cells in the liver preparations. Dividing diploid cells in both the marrow and liver showed the same chromosome change and were apparently derived from a common radiation-damaged ancestor. Author