Increased Litter Size in the Rat X-Irradiated during the Estrous Cycle before Mating

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Science  25 Aug 1967:
Vol. 157, Issue 3791, pp. 956-957
DOI: 10.1126/science.157.3791.956


Average numbers of ovulations, implantations, and living fetuses obtained from rats x-irradiated during the estrous cycle before mating are a function of both the radiation dose and the time of exposure during the cycle. Animals irradiated during metestrus or the day thereafter exhibit significant increases in the factors studied, while those irradiated on the 3rd day after metestrus maintain fewer implantations after exposure to 300, 500, and 600 roentgens, and fewer living fetuses after exposure to 100 to 600 roentgens.