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

The modification of the renal carcinogenicity of dimethylnitrosamine by actinomycin D and a protein deficient diet.

The effect of a single treatment with 30 mg dimethylnitrosamine (DMN) and 6 mug actinomycin D (ACT), given at different time intervals (ACT application to DMN, 2 h before, simultaneously, 5, 9 or 48 h later), was tested in female Sprague-Dawley rats in relation to renal carcinogenesis; additionally, the animals were fed either a normal or a protein deficient diet. The ACT treatment did not significantly modify either the kidney tumour incidence or the survival time in the different groups fed a normal diet. Nevertheless, there are indications that additional ACT application may shorten the latency period for DMN induced renal neoplasms or, when administered 5 h later than DMN, a slightly decreased and delayed tumour induction can be assumed. In groups fed a protein deficient diet, a significantly higher percentage of kidney tumour bearing animals as well as a shortened latency period were found when compared with the DMN group on normal diet, but these differences were independent of the additional ACT treatment 9 h later than DMN and were due to the protein deprivation. Morphologically, the tumours were of epithelial and mesenchymal type with a clear preponderance of the former type. Biochemical and morphological aspects are discussed