A new model for inducing malignant ovarian tumours in rats.

After the implantation of ovarian tissue into the spleen of gonadectomized female Sprague-Dawley rats (splenic ovary), luteomata and later benign granulosa or granulosa-theca cell tumours develop. Treatment of these rats with 7,12 dimethylbenz(a)anthracene (DMBA), given intravenously, 2 mg/kg body weight weekly, total dosage 40 mg/kg, immediately and especially 25 weeks after implantation of ovarian tissue into the spleen, led to malignant, partially metastasizing granulosa, and in one case theca cell tumours, 16-46 weeks after beginning the carcinogen treatment. No malignant neoplastic growth was seen when diethylnitrosamine (DEN), 20 mg/kg once weekly for life, was injected subcutaneously immediately or 25 weeks after implanting ovarian tissue.Since the normal, non-implanted rat ovary was not affected by DMBA treatment the malignant transformation of splenic ovaries in the respective experimental groups may be related to the increased stimulation by pituitary gonadotrophins and formation of luteomata or beginning granulosa and theca cell proliferations.