Effects of Low-Dose X-Irradiation on Early Mouse Embryos

Abstract

The effects of X-irradiation on the early mouse embryos at 0.5 or 1.5 days after fertilization were observed, with special regard to the incidence of death and of abnormalities. Doses used were 5 r, 15 r, and 25 r. The results obtained are summarized as follows: the number of resorbed embryos increased in irradiated groups, being dose-dependent; the rate of resorbed embryos in experimental groups irradiated at 0.5 and 1.5 days was not statistically different; a few animals with exencephaly and hindfoot polydactyly were obtained in experimental groups, but the difference between control and experimental groups was not statistically significant; abnormal fetuses with polydactylous condition on the forefoot were observed with relatively high frequency in both control and experimental groups; and histological observations revealed that cartilaginous ossification occurred on the extra fingerlike appendage. It can be concluded that the effect of low-level irradiation on early preimplantation mouse embryos was manifested primarily by an increased number of dead fetuses.