Induction of ovarian tumor in rats with N-butylnitrosourea

Considerable number (8.2 approximately 10.7%) of ovarian tumors were produced in Sprague-Dawley adult rats treated with multiple oral or intramuscular administration of heavy doses of N-butylnitrosourea. Histologically the tumor was a clear-cell adenma which reminded of embryonal testicular tissue. Electron micrograph revealed secretory function of the tumor cells. It was not possible to find histogenesis in the normal ovarian components.