Increased chromosome aberration levels in cells from mouse fetuses after zygote X-irradiation.

Cell cultures derived from skin biopsies of mouse fetuses X-irradiated at the zygote stage (2 Gy) were studied for the presence of chromosomal aberrations and micronuclei. In comparison with cells from control, unirradiated fetuses significantly higher spontaneous frequencies of aberrations per 100 metaphases and aberrant metaphases were found in cells which were obtained from normal fetuses and fetuses with gastoschisis after irradiation of the zygote. The proportion of aberrant metaphases in cells from fetuses with gastroschisis but not the frequency of aberrations per 100 cells was significantly higher than in cells from normal fetuses. Spontaneous aberrations were mainly chromatid and chromosome fragments. A significantly higher proportion of cells with micronuclei was observed in cells from fetuses with gastroschisis than in cells from control or normal fetuses after irradiation. The induction of chromosome instability in fetal fibroblasts after zygote irradiation has not previously been reported.