Formation of Fenestrae in Murine Liver Sinusoids Depends on Plasmalemma Vesicle-Associated Protein and Is Required for Lipoprotein Passage
Figure 6
Lipoproteins in capillaries and hepatocytes of Plvap-deficient animals.
A, PPD-labeled granular structures fill the lumen of kidney capillaries in a 3-week-old Plvap-/- mouse (arrows, boxed area, counterstain: Richardson's stain), while only erythrocytes are seen in the wild-type littermate (arrow, boxed area). B, The granular structures (black arrows) in the lumen of Plvap-deficient capillaries have diameters between 50 to 500 nm and are homogenously electron-dense. The particles are surrounded by extracellular fibrils with the ultrastructural characteristics of fibrin (white arrow) (TEM, lower panel shows higher magnification). C, PPD-labeled granular structures are seen in the lumen of liver sinusoids in a Plvap-/- mouse but not in a wild-type littermate (white arrows). The cytoplasm of the vast majority of Plvap-/- hepatocytes is densely filled with PPD-labeled granules (black arrows) which are rare in hepatocytes of wild-type littermates (black arrows). D, By TEM, numerous liposomes (black arrows) are seen in the Plvap-deficient liver indicating a pronounced microvascular steatosis. Hepatocytes of the wild-type animal contain large aggregates of glycogen (asterisks), which are absent in hepatocytes of the Plvap-deficient littermates. The lumen of Plvap-/- liver sinusoids is occluded by fibrillar fibrin (white arrows) suggestive of thrombus formation.