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Abstract
The epithelial cells of the rat lens have been extensively studied in regard to generation time and the phases of the cell cycle. On the basis of now available information it is possible to compare the effects of antitumor agents on this experimental system. In the present work the injury produced by x-rays and two widely used alkylating compounds is described. The three agents differ from each other in their mode of biological action. Experiments with a single exposure to 250 r and 1,000 r x-rays, single injections of Myleran (12.5 mg. per kilogram) and of triethylene melamine (1 to 2 mg. per kilogram) show that irradiation attacks the cells at multiple sites of the cycle; that Myleran inflicts injury to the cells in the G1, period with the signs of injury apparent as the cells prepare to divide. Triethylene melamine seems to act on some cells in the G2 period but primarily slows DNA synthesis with resulting prolongation of the S period.