Presence of DMBA-3H in the mouse ovary and its relation to ovarian tumour induction

Comparative morphological studies on the carcinogenic effect of 7,12-dimethylbenz(A)anthracene (DMBA) in normal or intrasplenic ovarian tissue of C3H mice

A single intravenous injection of 100 mg/kg body weight (b.w.) of 7, 12 dimethylbenz(a)anthracene (DMBA) induces a high percentage of ovarian granulosa cell tumours in C3H mice. After implantation of ovarian tissue into the spleen of gonadectomized female C3H mice similar tumours were found, resulting from an over-stimulation by pituitary gonadotrophins. In the present study the tumour development in intrasplenic ovarian tissue was observed after an additional single intravenous application of 100 mg/kg b.w. DMBA. It was found that the induction of granulosa cell tumours did not seem to be affected by the carcinogen injection whether 12 weeks before or 12 weeks after ovarian tissue was implanted into the spleen. The morphology of these neoplasms corresponds to the DMBA induced granulosa cell tumours in orthotopic ovaries. A direct carcinogenic effect of DMBA on ovarian cells in mice could not be demonstrated but there are indications that the additional DMBA application accelerated the destruction of the oocytes, which might result in a more rapid intrasplenic tumour induction.

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.