Abnormalities in the Hepatic Sinusoids: Pathological Basis of Self-perpetuation of Liver Cirrhosis

The hepatic microcirculatory system consists of four microvascular components: the terminal portal venule and hepatic arteriole as two afferent vessels, the sinusoids corresponding to the capillary bed, and the terminal hepatic venule as an efferent vessel. This microvascular unit is the basis for the simple liver acinus, which has been proposed as the smallest functional unit of the hepatic lobule [1]. The major components among these microvessels are the hepatic sinusoids, which are characterized by the presence of the sieve-like pores [2], i.e., the sinusoidal endothelial fenestrae (SEF), and by the absence of the basement membrane beneath the sinusoidal endothelial cells. These ultra-structural characteristics reflect the active exchange of metabolites between the sinusoidal blood and the hepatocytes, maintaining constant liver cell functions. In this respect, impairment of the sinusoidal blood flow directly leads to a variety of liver cell dysfunction.