STUDIES ON THE BIOLOGICAL EFFECTS OF NEUTRONS AND Co$sup 60$ $gamma$-RAYS IN MICE. I. BIOLOGICAL EFFECTS OF NEUTRONS IN MICE

Mice were irradiated by cyclotron neutrons, including gamma rays, and the changes of the body weight, peripheral blood picture, and histological findings were observed. In group 1, given 1.1 x 10/sup 1//sup 1/ n/cm/sup 2/, severe intestinal damage snd leukopenia were observed. The animals died with a mean survival time of 3 days 3 hours. Their death was probably the acute death due to intestinal radiation. In group 2, given neutrons of a dose between groups 1 and 3, radiation effects were most severe on the 3rd to 5th day and all mice of the sm strnin died about the 7th day. Leukopenia and infection may be impontant causes of death. In group 3, given 4.7 x 10/sup 1//sup 0/ n/cm/sup 2/, gross changes became normal by the 4th week, but precise examination revealed longcontinued radiation effects. The radiation dose wss in this case in the sublethal range. The conclusion was that the radiation effects of neutrons are almost the same as those of the other ionizing radiations. (Absts. Japan. Med., 1: No. 7, 1960.)