Experimental induction of colonic carcinomas in rats. Analysis of factors influencing upon the incidence.

A method to make a diverted segment of the colon keeping direct continuity to the main colonic lumen was introduced to study carcinogenesis in the colon of rats. This method was proved to be useful for analyzing several factors influencing upon cancerization in the colonic mucous membrane. Macroscopical colonic neoplasia were induced in nearly 80% of rats treated with N-methyl-N'-nitro-N-nitrosoguanidine introduced into the colonic lumen through the diverted segment. Neoplastic lesion of the mucous membrane developed mainly in the colonic segments which were in direct contact with intestinal content. The importance of intestinal content and colonic microflora was discussed and reviewed. One epithelial cell line was established from one intraperitoneal metastatic deposit of a huge colonic carcinoma induced by the carcinogen. This cell line has been maintained in tissue culture. The liver was susceptible to the carcinogen, and multiple cystic lesions were observed after intracolonic administration of the chemical.