Abstract
Pregnant mice of B72 strain from crosses with Swiss albino males received X-irradiation at a dose of 200r through a whole body exposure, at various days ranging from 0.5 to 15.5 days of gestation. The effects of X-rays on embryos were examined at varying days of gestation. The results are summarized as follows:
1. A number of malformations was observed in embryos irradiated at 8.5 to 12.5 days of gestation. A frequency in total of abnormal embryos was found to be 27.7%. The abnormalities here observed were anophthalmia, exencephalia, short snout, syndactylia, polydactylia, deformed tail, short tail and malformed arms.
2. An average number of litters was observed to be 5.1 for 32 irradiated mothers, and 6.0 for 5 non-irradiated ones. No remarkable difference of litter size occurs between irradiated and non-irradiated mothers.
3. In total of 166 embryos derived from irradiated mice, 88 were male and the remaining were female. There is no marked deviation of sex-ratio in embryos derived from irradiated embryos.
4. An average weight of embryos derived from mothers which received irradiation at 8.5 to 12.5 days of gestation was considerably lower than that of control embryos. The minimum weight was found in the embryos irradiated on the 11.5th to 12.5th day.
5. Body-length/tail ratio was between 2.1 and 2.5 in control embryos, while that of embryos from mothers irradiated at 8.5 to 12.5 days of gestation was generally over 2.5, due to short tail.
