The fine structure of rat liver sinusoids, space of Dissé and associated tissue space

Abstract Three structurally distinct zones are present in the liver sinusoid. The endothelium and basement (boundary) membrane of the portal vein extend uninterruptedly into the peripheral zone. The intermediate zone, comprising 90% or more of the length of the sinusoid, possesses a fenestrated lining and no basement membrane. The short central zone has unfenestrated endothelium and a basement membrane. Both are continuous with those of the central vein. The space of Dissé encircles all three zones of the sinusoid. It contains fat storage cells, perisinusoidal cells, numerous microvillae of liver cells and reticular fibers. These fibers are bundles of unit collagen fibers enclosed by cytoplasm of nearby cells. The space of Dissé is continuous with the tissue space at both ends of the sinusoid. The liver cells lack a basement membrane whether they abut on the space of Dissé or on the tissue space proper. The unique feature of liver fine structure is the combination of fenestrations and lack of basement membranes in the intermediate zone of the sinusoid. Blood plasma is thereby afforded intimate contact with the parenchymal cells and has access to the tissue space at both ends of the sinusoid. This structural situation fits the known facts of liver function.