AIM:To study oval cells’pathological characteristics andrelationship with the occurrence of hepatocellularcarcinoma(HCC);to observe the form and structuralcharacteristics of oval cells;to explore the expressioncharacteristics of C-kit,PCNA mRNA and c-mycgene duringthe occurrence and development of HCC and the effect ofulinastatin(UTI)on C-kit and PCNA expression.METHODS:One hundred and twenty-five SD rats fed on3.3’-diaminobenzidine(DAB)to construct HCC models weredivided into control group,cancer-inducing group and UTIintervention group.In each group,rat liver samples werecollected at weeks 2,4,6,8,10,12,14,16,18,20,22 and24 respectively to study pathological distributioncharacteristics of oval cells in the process of carcinogenesisunder optical microscope.Oval cells were separated bythe methods of improved density gradient centrifugationand their structural characteristics were observed underoptical microscope and electronic microscope respectively;theoval cells expressing C-kit and PCNA in the collected sampleswere observed by the methods of immunohistochemistry andimage analysis and the expression of c-myc mRNA was alsodetected by reverse transcription polymerase chain reaction(RT-PCR).RESULTS:Oval cells proliferated firstly in the portal areathen gradually migrated into hepatic parenchyma in theinducing group and intervention group.The oval cellsdistributed inside and outside the carcinoma nodes.Theoval cells presented the characteristics of undifferentiatedcells:a high ratio of nucleolus and cellular plasm andobvious nucleoli,rare organelle in plasm.Only a fewmitochondria and endoplasmic reticulum and some villus-like apophysis on surface of cells could be seen.Cellsstained with C-kit and PCNA antibody were mainly ovalcells distributed in the portal area.The expression of c-myc mRNA increased with the progression of HCC.However,in the intervention group,UTI could retard itsincrease.CONCLUSION:Oval cells work throughout the developmentof HCC,and might play important roles in this process.c-myc gene may be a kind of promoter gene of HCC,andplay a key role in hepatic injury and development of HCC.UTI could retard the occurrence of HCC. AIM: To study oval cells’ pathological characteristics and relationship with the occurrence of hepatocellular carcinoma (HCC); to observe the form and structural characteristics of oval cells; to explore the expression characteristics of C-kit, PCNA mRNA and c-myc gene during the occurrence and development of HCC and the effect ofulinastatin (UTI) on C-kit and PCNA expression. METHODS: One hundred and twenty-five SD rats fed on 3.3’-diaminobenzidine (DAB) to construct HCC models weredivided into control group, cancer- inducing group and UTIintervention group.In each group, rat liver samples were collected at weeks 2,4,6,8,10,12,14,16,18,20,22 and 24 respectively to study pathological distribution characteristics of oval cells in the process of carcinogenesisunder optical microscope. Oval cells were separated by the methods of improved density gradient centrifugation and their structural characteristics were observed underoptical microscope and electronic microscope respectively; theoval cells expressing C-kit and PCNA in the collected samples were observed by the methods of immunohistochemistry and image analysis and the expression of c-myc mRNA was alsodected by reverse transcription polymerase chain reaction (RT-PCR) .RESULTS: Oval cells proliferated in the portal areat gradually migrated into hepatic parenchyma in the induction group and intervention group. The oval cells presented the characteristics of undifferentiated cells: a high ratio of nucleolus and cellular plasm and allogeneic nucleoli, rare organelle in plasm. -like apophysis on surface of cells could be seen. Cellsized with C-kit and PCNA antibodies were mainly oval cells distributed in the portal area. The expression of c-myc mRNA increased with the progression of HCC. Host, in the intervention group, UTI could retard itsincrease.CONCLUSION: Oval cells work throughout the developmentof HCC, and might play important roles in this process.c-myc gene may be a kind of promoter gene of HCC, and play a key role in hepatic injury and development of HCC. UTI could retard the occurrence of HCC.