[Bile canaliculi in chronic hepatitis (ultrastructural study)]

The biliary pole of the hepatocytes is formed by the canaliculus, the intracytoplasmic organelles, the pericanalicular cytoskeleton and by canalicular membranes. As a rule, the set of these sub-structures give risk to the biliary secretion. At present, the canaliculi are not considered as "fixed" structures, but rather entities that can be formed and modulated by intra and extra hepatic factors aiming of regulating the bile secretion in relation to metabolic events and to the body's requirements. To this end, a role is played by hormones, metabolites, drugs or toxic substances, etc. Data reported in the literature show that they change their profile in situations of intra-extrahepatic cholestasis. That is, they show ectasia, almost deprived of microvilli and with a dense pericanalicular matrix. On the basic of this theoretical premises, the Authors have aimed at verifying the ultrastructural features of the canaliculi in the case of chronic hepatitis showing no sign of cholestasis. The parameters taken into consideration are the same as the ones which result to be modified during cholestasis: diameter of canaliculi, number of microvilli and pericanalicular matrix. For this purpose 25 cases of persistent chronic hepatitis and 25 cases of active chronic hepatitis have been utilized without any clinical or humoral sign of cholestasis. Needle biopsy specimens of hepatic parenchyma have been studied both at the transmission electron microscopy and at scanning electron microscopy. The result obtained can be summarized as follows: 1) The canaliculi are impaired both in the cases of persistent chronic hepatitis and in those of active chronic hepatitis (they develop ectasia, with very-few microvilli and with a thickened pericanalicular matrix). 2) Within the same case, different degrees of changes have been observed. 3) The above changes can be mostly observed at the level of the canaliculi surrounded by hepatocytes which are characterized by hydropic swelling. 4) Such a correlation (canalicular changes-hydropic degeneration of the hepatocytes) permits to assume that the causes of those changes in the canaliculi are to be ascribed to alterations of the pericanalicular microfilaments.