Summary
Beginning at 100 days of age, LAF1 mice were exposed to 12 or 14 r per day of 60Co γ-rays. In the unirradiated animals, the degree of intercapillary glomerulosclerosis was relatively constant from 100 to 500 days of age, after which it progressively increased. The animals receiving 24 r per day did not survive beyond 500 days of age; their kidneys were like those of the unirradiated animals. In animals receiving 12 r per day, the degree of intercapillary glomerulosclerosis after 300 days of age was only a little greater than in the unirradiated animals, though consistently so. This was true even in 700-day-old animals that had received an accumulated dose of 6600 r. The small renal arteries and arterioles were not altered. Thus continued small daily doses of γ-radiation resulted in much less renal damage than had been found in a previous study with single doses of x-rays.