[Ultrastructure of Ito cells in fibrotic liver diseases].

Authors have studied the ultrastructure of Ito-cells in percutane needle-biopsy samples of hepatic tissue from 36 patients. In 3 samples no alteration was found, in four only moderate steatosis occurred without fibrosis. In four samples portal, in ten centrilobular and in five periportal fibrosis was detected, while in five samples cirrhosis was pointed out. In the intact liver, Ito-cells occur not only in the spaces of Disse but also in the wall of the central vein. In portal fibrosis Ito-cells were similar in location and structure to those in the non-fibrotic liver. In centrilobular and periportal fibroses as well as in cirrhosis Ito-cells in the fibrotic parenchyma areas were either localized in the accumulated connective tissue or at the border of connective tissue and hepatocytes. These interstitial Ito-cells contained small amount of lipid, abundant dilated rough endoplasmic reticulum filled with a flocculent material, well-developed Golgi-complex and often bundles of 5 nm thick filaments with dense territories. Close to the Ito-cells immature collagen-fibrils and basement membrane-fragments were seen. A close relationship was pointed out between activated Ito-cells and lymphocytes. In parenchyma areas away from fibrotic foci the structure of Ito-cells was comparable to that of Ito-cells in intact hepatic lobules. Observations suggest that Ito-cells are related to fibroblasts and myofibroblasts and play a role in the pathogenesis of fibrosis occurring in human liver diseases.