Fenestrated Endothelium of the Liver Sinusoids of the Guinea Pig as Revealed by Scanning Electron Microscopy

• Published in: Archivum histologicum japonicum Vol. 37; no. 1; pp. 15 - 24
• Main Authors: ITOSHIMA, Tatsuya, KOBAYASHI, Toshinari, SHIMADA, Yoshihiro, MURAKAMI, Takuro
• Format: Journal Article
• Language: English
• Published: Japan International Society of Histology and Cytology 1974
• Subjects: Animals; Capillaries - ultrastructure; Endothelium - ultrastructure; Guinea Pigs; Hepatic Veins - ultrastructure; Kupffer Cells - ultrastructure; Liver - ultrastructure; Microscopy, Electron, Scanning; Portal System - ultrastructure; Staining and Labeling
• ISSN: 0004-0681
• DOI: 10.1679/aohc1950.37.15

The endothelium of the liver sinusoids in the guinea pig was studied with the scanning electron microscope, using specimens fixed by perfusion and treated with the revised tannin-osmium method of MURAKAMI (1974) and devoid of metal coating. The endothelium of the liver sinusoids was provided with numerous intracellular and some intercellular fenestrae, whose size and population varied by their position in the lobule. Larger fenestrae measuring 0.5 to 3.0μ in diameter occurred in the endothelium near the central veins. The fenestrae became smaller and fewer towards the periphery of the lobules and, close to the distributing veins they measured less than 0.3μ in diameter. Besides these fenestrae, groups of micropores were found to form sieves in the concavities among the reticular crests of the endothelial sheet. The nuclear swelling and the cytoplasmic crests also possessed small pits which likely represented pinocytotic invaginations. Some parts of the sinusoidal wall in the periportal area were formed by the cells which protruded into the lumen of the sinusoids and horizontally extended their processes like star-fish. These cells which had no fenestrae were considered to be Kuppfer cells. Just below the endothelium there were observed, through its fenestrae, cells with long processes extending over microvilli of hepatic cells. These cells were considered to correspond to the fat-storing cells of ITO. Discussion was made on the functional significance of the fenestrae, especially of their positional differences.