Neoplasms in ovaries of CBA mice 90Sr-treated as foetuses.

Female CBA mice were 90Sr-contaminated in utero by amounts ranging from 46 to 740 kBq given to the pregnant dams on the 19th day post coitum. The females were killed at an average age of 10 months. The ovaries were microscopically analysed and morphologic changes were recorded. Multiple corpora lutea were frequent in all but the two highest dose groups. Ovarian cysts were frequent as well. Proliferative events such as hyperplasia of luteinized interstitial cells and down-growths of the germinal epithelium did not occur until a dose of 185 kBq. The findings indicate a non-linear dose-tumor relationship, but also a direct proportion of animals with down-growths and those with tubular adenomas beyond a threshold of 14 per cent.