Methylhydrazine tumorigenesis in Syrian golden hamsters and the morphology of malignant histiocytomas.

A 0.01% solution of methylhydrazine was administered daily in the drinking water of 6-week-old randomly bred Syrian golden hamsters for the remainder of their lifetime. The treatment gave rise to malignant histiocytomas of liver and tumors of the cecum. Thirty-two % of the females and 54% of the males developed malignant histiocytomas whereas among the controls no such lesions were seen. The incidence of tumors of cecum was 18% in females and 14% in males, compared to 1% in the controls. Macroscopic, light and electron microscopic, and histochemical investigations of the liver lesions showed the characteristic appearance of malignant histiocytomas. The histological involvement of the tissues by the tumors is presented. The fine structure of the malignant histiocytoma, the nuclei, and cytoplasms with organdÃ-esof the tumor cells are described and illustrated in detail. Methylhydrazine is a rocket fuel component, and some of its derivatives have been proposed for use in treating certain human cancers. Because it has been shown to produce tumors in mice and now in hamsters, precautions should be taken concerning its use.