Abstract: Objective To establish an orthotopic colon tumor and metastasis model by the coloclysis of MNU in SD Rat, to observe the carcinogenesis development and the metastasis process. Methods SD Rats were given the MNU clyster，the clinical symptom was checked, the tumor growth, metastasis of the rat were observed. To respectively sacrifice 12 SD rat every time at 8, 12, 16 weeks later, observe the tumor in situ and the metastasis. Evaluate the effect of this colon cancer model through pathological methods. Result None of the SD rat died, 8 weeks later，clinical symptom show hematochezia and lymphadenectasis，16 weeks later, 91.7% rat formed colon neoplasma and many lymphadenectasis，pathological examination confirm the colon adencarcinoma with lymph node metastasis. Conclusion The successful establishment of orthotopic colon tumor model by the coloclysis of MNU in SD Rat. The induction process is convenience and utility, the model has the colon carcinoma autogenesis development successfully.The orthotopic tumor and metastasis model provide useful tools for the study of mecha-nism of metastasis and its treatment of colon cancer.

Key words: MNU, Colon carcinoma, Animal model, Lymphonode metastasis