The effect of normal ovarian tissue on the ovarian tumorigenesis in x-irradiated mice.

小室正人:東 京大学理学 部動物学教室,東 京都文京区本郷7-3-1,〒113 1 Present address: Department of Anatomy , The Teikyo University School of Medicine, Kaga 2-11-1, Itabashiku, -T173. The ovarian tumors induced by X-ray irradiation were histologically examined in ddY/F and C3H/Tw strains of mice 15 months after irradiation. Luteomas were developed predomi nantly in ddY/F mice after whole-body irradiation and tubular adenomas in C3H/Tw mice. However, when one ovary was shielded from irradiation in ddY/F mice, no ovarian tumors were found in any of the irradiated contralateral ovaries. After the removal of the normal ovary at 1 or 6 months after irradiation, the increase in the incidence of tubular adenomas and the decrease of the luteomas were resulted in ddY/F mice when examined at 15 months after irradiation. No tumors were induced in the ovaries which were grafted subcutaneously after the X-ray irradiation of the recipient. These results suggested that hormonal conditions especially during early stages of tumorigenesis may determine the type of ovarian tumors.