Objective To establish a mouse model of lung adenocarcinoma induced by N-ethyl-N-nitrosourea (ENU) in mice and to characterize its tumor pathology. Methods BABL/c mice were used to establish the lung cancer model. On the 17^th day of pregnancy, the parental female mice received intraperitoneally ENU or buffer injection, respectively. The 32-week old offsprings were sacrificed and entire lungs were harvested and processed for histopathological observation of HE stained semiserial sections. The pathological features of the lung tumors were assessed. ResultsMultiple tumors in offspring''s lungs were induced transplacentally by a single injection of ENU. The tumors were at different development stages of adenoma or adenocarcinoma. The adenocarcinomas were classified as bronchioloalveolar-like adenocarcinoma (female:5/6; male:4/6) and adenocarcinoma of various differentiation (female:4/6; male:5/6). The frequency of cancer development was 5 out of 6 mice in both sexes. The frequency of tumors which developed into malignant tumors was 16 out of 43 tumors in female and 12 out of 31 tumors in male mice. ConclusionsWe have successfully established a mouse model of lung adenocarcinoma in mouse offsprings by a single injection of ENU in pregnant female mice. The heterogeneous presentation of tumor pathology indicates the complex molecular mechanisms of its carcinogenesis.