OBJECTIVESTo study the dynamic change of hepatic oval cells (HOC) in the process of rat liver cirrhosis formation induced by dimethylnitrosamine (DMN), and to explore its pathophysiology significance.

METHODSA rat cirrhosis model was established by using DMN. Microscopical and electronmicroscopical changes of HOC were examined. Thy1.1 was detected by immunohistochemical method at different times. The ratio of HOC was checked using image pattern analysis and Western blot. The number of HOC was counted microscopically.

RESULTSAt the 4th week after DMN administration, the liver fibrosis was at its peak, with false lobules formation combined with large areas of hemorrhage and necrosis. The fibrosis started to minimize at the 6th week, and also the inflammatory changes at the 8th week. Thy1.1 positive stained cells dispersed at the 2nd week; increased at the 4th week around fiber septa; reached its peak at the 6th week, then decreased at the 8th week. The results of image pattern analysis, cell counting under light microscope and Western blot were constant, with the highest cell numbers at the 6th week, and dropped at the 8th week. The ultrastructure of HOC was characterized by their small sized, oval nuclei, and higher nucleus/plasma ratio.

CONCLUSIONDuring the formation and reduction of rat cirrhosis caused by DMN, Thy1.1 stained HOC showed notable dynamic change, which may play an important role in the cirrhotic process.