Further studies on the effect of radiation during the storage of frozen 8-cell mouse embryos at -196°C

Abstract

Frozen 8-cell mouse embryos were treated with radiation doses of 0, 10, 50, 100 or 200 cGy-γ-rays at a dose rate of ≃ 5cGy/day. After thawing the embryos were scored for normal morphological appearance and for development to morulae and blastocysts after 24 h in culture. Embryos from each treatment were then separately transferred to the uteri of pseudopregnant foster mothers which were killed at Day 14 of pregnancy. There was no effect of radiation on morphological appearance, development to morulae and blastocysts, implantation rate, or on the ratio of five fetuses to the number of transferred embryos. As there appeared to be no detrimental effect of up to 200 cGy on frozen 8-cell mouse embryos and, as this is the equivalent of ≃ 2000 years of background radiation, it is concluded that normal level of background radiation would not be a hazard to the long-term storage of mammalian embryos.