Development of ovarian tumors experimentally studied in mice by 60Co-ray irradiation

Female C3H strain mice aged 5 to 6 weeks were exposed to a single dose of 400 Rad irradiation to their lower abdomens and the morphological changes of their ovaries were observed until 72 weeks after irradiation. The incidence of tumor development increased gradually from 34 weeks after irradiation till 72 weeks, when ovarian tumors were noted in more than 90% of the animals. Three types of ovarian tumors developed after a prolonged period, postirradiation: tubular adenoma, granulosa cell tumor and luteinizing tumor. Mixed tumor types account for 68% of the tissue examined. The tubular adenoma is believed to arise from the germinal epithelial inclusion cyst, the granulosa cell tumor and luteinizing cell tumor arise from the interstitial cells. In the case of the granulosa cell tumor, it is believed that tumor cells one capable of secreting estrogen, because vaginal smears demonstrated estrus and histological sections of endometrium demonstrated hypertrophy.