Weibel-Palade body release in IVC endothelium after flow restriction. IVCs from WT mice 6 hours after stenosis had been applied were rapidly excised and snap-frozen in Optimal Cutting Temperature compound (Tissue-Tek). The part of IVC within 2 mm from the stenosis site was sectioned, immunostained for VWF (green), platelet αIIb (red), counterstained for nuclei (blue), and photographed by an inverted fluorescent microscope. Two types of endothelial zones were observed after 6 hours of stenosis: (A) a nonactivated endothelial zone with the typical WPB (green, WPBs) staining pattern and (B) a zone of activated endothelium with no obvious WPB staining. Leukocytes (L) and platelets (P) are adherent to the endothelial cell layer (EC) only in panel B. Subendothelially located VWF is designated with arrowheads. (C) Control staining with nonspecific IgG used instead of primary antibodies. Representative images of 3 mice are shown. Bar, 10 μm.