The vascular pole of hepatocytes: structure, function and pathology

Structural and functional subdivision of the hepatocyte into a sinusoidal (vascular) zone, a lateral zone and a peri-canicular zone (adjacent to the bile canaliculi) highlights certain peculiarities of the vascular hepatocyte pole. In contrast to the total cytoplasm, this area is characterized by a high volume of mitochondria, altered peroxisome content, a high concentration of lipids and the absence of Golgi-apparatus. Of critical importance is the sinusoidal cell membrane: at birth, the hepatocyte of the rat bears some 1,000 microvilli, rising to 4,600 in the mature animal. The surface to volume ratio of this part of the cell is more than 250% of the overall cell ratio. The ectoplasmic area beneath it is of importance to the structural integrity and function of the cell membrane itself. Pathological changes such as formation of blebs, shedding of cytoplasm, detachment of portions of the vascular pole, emergence of phagocytic processes, production of atypical substances (i.e. amyloid precursors), are closely and interactively related to pathologic processes of other elements of this region (non-hepatocyte, space of Disse). The peri-sinusoidal functional complex, may have an importance for the pathology of the liver which has not been fully appreciated to date.