Residual radiation damage in mouse skin 5 to 8 months after irradiation.

Residual injury from large doses of x-rays or neutrons given 5-8 months earlier was assessed by the response of the skin to further doses of 250 kV x-rays. The "dose remembered" was assessed by single test doses. Two doses separated by 24 hours or 7 days were given to assess the capacity for repair of sublethal injury and recovery by proliferation. About 10% of the pretreatment dose was "remembered" 5-8 months later. The capacity for repair of sublethal injury and proliferation was similar in controls and animals receiving 1000-3000 rads as pretreatment. These results apply to basal layer epidermal cells and may differ from those of more slowly dividing populations.