Studies on dominant lethal mutations in third generation rats reared on an irradiated diet

Third generation male rats fed on gamma irradiated (0.2 Mrad and 2.5 Mrad) and unirradiated diets were studied in an attempt to detect induced mutagenic effects. Each rat was provided with two virgin females, and the females were replaced by a fresh pair after 1 week. Sequential mating was continued for 3 weeks; a further mating was carried out during the sixth week. The females were killed eleven days after the last day of caging, and their uterine contents examined for viable and dead (dead embryos and deciduomata) implants. Pre- and post-implantation lethalities were assessed and statistically evaluated. Results provided conclusive evidence of the lack of induction of dominant lethal mutations in the third generation of male rats fed on irradiated diets. (U.K.)