Electron microscopic mesenchymal response in chronic viral hepatitis

BACKGROUND/AIMS: This study was designed to clarify the fine structures of the hepatocytes and mesenchymal tissues in chronic hepatitis according to severity. METHOD: For the purpose of elucidating the ultrastructural characteristics of mesenchymal tissues, liver biopsy specimens were studied by light and electron microscopy in 20 patients with chronic hepatitis. RESULTS: 1) Hepatocytes in mesenchymal tissues were thought to be in the stage of regenerated or degenerated process. 2) Regenerating nodules were surrounded by a basement membrane-like materials in the space of Disse. 3) In the widened Disse space the deposition of collagen fiber bundles and increased numbers of hepatic stellate cells in necrotic area were observed. 4) In necrotic areas, hepatic mesenchymal cell response including an increase of collagen fibers and fibroblast, angiogenesis, and a proliferation of bile ductules were also observed. CONCLUSIONS: These observations suggest that the fibrosis in severe chronic hepatitis was accompanied by the mesenchymal response including the proliferation of hepatic stellate cells, fibroblasts, capillarization of Disse space, and mesenchymal proliferation. Finally, this fibrosis observed electron microscopically may be a cause of functional hepatic failure.