Intra-uterine death in outbred strain of mice irradiated with low-doses of X-radiation at different ages

Female mice of outbred Swiss strain were irradiated with low-doses (4, 8, 16 and 32 R) of X-radiation at the age of 10, 26 and 52 weeks. Twenty hours after exposure 3 females from each experimental group were mated with a male for a week. On the 17th and 20th day after mating all females were killed and the numbers of live and dead implants were counted. Additional groups of the same age and size served as controls. The percent of pregnant females in all experimental and control groups was related to the age of a female. The lowest number of pregnant females has been found in oldest (52 wk.) females. Also the number of dead implants was significantly higher in oldest females. Irradiation did not influence the pregnancy ability, whereas the number of dead implants was statistically higher in mice irradiated with 32 R at the age of 26 and 52 weeks. (author)