Various degrees of susceptibility of different stocks of rats to N-2-fluorenyldiacetamide hepatic carcinogenesis.

Outbred Osborne Mendel, Japanese, Wistar, NIH Black, and Sorague-Dawley male rats 12 weeks of age ingested 0.025% N-2-fluorenyldiacetamide in a semisynthetic diet Sprague-Daeley and NIH Black male rats were most susceptible to the development of carcinomas and cirrhosis of the liver and also had the highest incidence of metastases. More and larger carcinomas per liver and more poorly differentiated and undifferentiated carcinomas were found, as well as more advanced cirrhosis, Japanese and Wistar male rats were susceptible, but less so, to hepatic carcinogenesis and cirrhosis. These rats had fewer and smaller hepatic carcinomas per liver, and the neoplasms were well differentiated. By contrast, Osborne Mendel male rats were least susceptible to hepatic carcinogenesis and cirrhosis.