Abstract: Objective To study the dynamic processes of bladder tumor in Wistar rat induced by intravesical irrigation of the carcinogen,MNU and discuss how to establish an appropriate animal model of bladder tumor. Methods Sixty Wistar rats were randomly divided into 3 groups. The model rats were intravesically affused with MNU as carcinogen to induce bladder tumor every two weeks. Rats were sacrificed in different periods. Results In total of 60 rats , 58 of them had finished the experiment while 2 rats died during the period.In cancer induced group(VINU group) there were 39 survived during the experiment in which 37(92.5%) of them were confirmed by pathology to be bladder cancer and other 2 rats(5%) were atypical dysplasia(hyperplasia).Thirty three rats were diagnosed to be positive bladder tumor in 37 rats combined with urinary HE and AO pigmentation while the positive ratio is 89.2%. Conclusion Bladder tumor induced by MNU is highly resemble with that of human beings in both histologic and pathologic character.lt is expected to have good foreground to diagnose bladder tumor in animal model combined with urinary HE and AO pigmentation.

Key words: Bladder tumor, Intravesical irrigation, Carcinogen, N-methel-nitrosourea(MNU)