Tumors of the nervous system induced by ethylnitrosourea administered either intracerebrally or subcutaneously to newborn rats

Abstract

✓ Tumors of the nervous system grew in rats treated at birth with ethylnitrosourea through intracerebral or subcutaneous routes and in fetal rats treated through the mother. In 80% to 85% of the rats, single and multiple tumors developed in the brain and spinal cord regardless of the route of administration. Gasserian neurinomas, oligodendrogliomas, and oligogendroglial foci were the most frequent neoplasms. General morphological aspects and frequency of tumor localizations in relation to drug administration route are discussed. Thymidine incorporation into DNA, and RNA/DNA ratio, were evaluated in order to estimate tumor proliferation rate and growth. Desmosterol, a characteristic sterol of brain tumors, was detected in all the tumors. Regions of the brain and spinal cord of treated rats showed the presence of microscopic pretumoral areas (oligodendroglial foci) which incorporated thymidine into DNA in contrast to the brains of control rats.