Data on transgenerational genomic instability after irradiation of female mammals are scarce. Irradiation of mouse mature preovulatory oocytes with 1Gy of X-rays was shown to result in the presence of chromosome rearrangements in the liver cells of 14% of the 14.5-day embryos [40].More recently, a significant increase in the frequency of aberrant metaphases as well as of the breaks per total metaphases was reported in the fibroblasts of fetuses issued from female rats that had been X-irradiated with a dose of 5Gy [41]. In this case, irradiation had been performed 45–60 days before mating, ensuring that the fetuses that were analyzed originated from oocytes that were at the resting (immature) stage at the time of irradiation. In a very recent study [42], the frequency of ESTR mutations was investigated in the germline and somatic tissues of the offspring of male and female mice that had been X-irradiated in utero with 1Gy during late organogenesis (day 12 of gestation, corresponding to meiotic initiation in germ cells).