Abstract
After 12 oral applications of 80 mg/kg MNNG as a suspension in 30% aqueous ethanol at weekly intervals, 98 Sprague-Dawley rats died with multiple tumors of the forestomach after a medium latency period of 226 days. Histological examination showed generalized papillomatosis developing into keratinizing squamous cell carcinomas with infiltrative growth in 88/98 (89%) animals. Tumorigenic lesions in the glandular stomach ware only observed in 3/98 rats. In two of these animals, mucosal adenocarcinomas were found and in the third a leiomyosarcoma. In about 30% of the animals treated with MNNG, degenerative liver changes were found, especially single cell and focal necroses, cystic alterations, and bile-duct proliferations.
Key words: N-Methyl-N′-nitro-N-nitrosoguanidine, tumors in forestomach, glandular stomach, liver
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