The Effects of Irradiation with Phosphorus-32 on the Viability and Growth of Rat Embryos

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Abstract
The effects of [beta]-radiation on rat embryos 6 to 10 days of gestational age were studied by the intraperitoneal administration of radioactive phosphorus (p32) to pregnant females. The LD50 is that dose of P32 which, when administered to the mother, kills 50% of the fetuses by the 14th day of gestation. These values were: day 6, 0.46 mc; day 8, 0.57 mc; day 9, 0.77 mc; and day 10, 1.29 mc. The radiophos-phorus uptake was also studied at several doses, and the radiation doses to the embryo were calculated for each day of gestation. By interpolation of the uptake data, it was possible to estimate the radiation dose received by an embryo at the LD50 level. For the first 4 days after injection these were: day 6, 300 rep; day 8, 450 rep; day 9, 560 rep; and day 10, 925 rep. Uptake was proportional to the injected dose, indicating no major interference with P metabolism. All doses of P32 depressed embryos weight, as measured on the 14th day of gestation. The magnitude of the depression followed the same pattern as did the LD50, earlier embryos being more sensitive.