The purpose of this work is to maintain a colony of inbred Buffalo Strain rats in whom we have successfully induced adenomas and adenocarcinomas of the colon following the subcutaneous administration of 1,2-dimethylhydrazine and have been able to transplant the tumor both intraperitoneally and subcutaneously through five passages. Using this laboratory model we propose to study in vivo, using histological techniques, the morphogenesis of these tumors by means of periodic biopsies. Furthermore, we intend to provide interested investigators with this cell line which we will maintain in our laboratory.