[Improvement of mouse model for thymic lymphoma induced by N-methyl-N-nitrosourea]

The objective of this study was to elevate the tumorigenic rate of animal model with thymic lymphoma induced by N-methyl-N-nitrosourea (MNU) and to reduce the mortality of this mouse model. The injection regimen and experimental cycle were improved on the basis of previous experiments. The male and female C57BL/6 mice were injected by the intraperitoneal route with MNU solution at different dosages in the first week and the 4th week respectively. Following injection of MNU, the general features of the mice were observed. All mice were sacrificed for autopsy before the 24th experimental week. Complete gross examination was performed for detection of tumor masses. The pathologic and immunohistochemical methods were used to identify the origin and subtype classification of the neoplasm. The results showed that at the 25th week the incidence of thymic lymphoma in mice injected with MNU was 83.3% (55/66), the mortality was 7.6%. In conclusion, improving the program and changing the experimental cycle can increase the tumorigenic rate in the mouse model induced by MNU from 67.5% to 83.3% and reduce the mortality from 10% to 7.6%.