Colonic neoplasms in mice produced with six injections of 1,2-dimethylhydrazine.

A highly effective but reduced injection schedule for the induction of the colon cancer in CF1 female mice is reported using 6 subcutaneous inoculations of 1,2-dimethylhydrazine at a dose level of 20 mg/kg body weight. Between the 20th and 45th week of the experiment, 83% of the animals were tumor-bearing with a frequency of 2.1 colonic neoplasms macroscopically visible per mouse. Tumors were isolated in nature and primarily located in the distal large bowel. Some degree of carpeting of the colonic mucosa and uncountable numbers fo tumors occurred in 30% of mice and these areas of confluent neoplasms also occurred predominantly in the distal colon. This spectrum of distribution of tumors closely parallels that seen in man thus enhancing the value of this time conserving colon tumor model.