Fig. 7. PAR-3 is expressed by endothelial cells in various tissues. Cryostat sections of tongue, heart endocardium and a heart artery, as well as of mesenterial lymph node, were incubated with a polyclonal antibody against PAR-3. Bound antibodies were visualized by peroxidase-conjugated secondary antibodies. Antibodies against PECAM-1, von Willebrand factor (vWF) and the MECA-79 epitope were used as endothelial-specific markers. In negative control samples (neg. ctrl) the staining procedures were performed without primary antibodies. In the bottom panels, high endothelial venules appear as regions with lower cell densities. Note that PAR-3 is completely absent from high endothelial venule endothelial cells. Bars, 50 µm.