Specific functions of neutrophil granules and secretory vesicles in relation to diapedesis and phagocytosis. (1) Primary contact between endothelium and circulating neutrophils is established via selectins and their ligands, which causes the neutrophils to roll along the activated endothelium. This contact may transduce signals in the neutrophils that mobilize secretory vesicles. (2) Integration of the membrane of secretory vesicles and its associated CD11b/CD18 enhances the potential of the neutrophil for firm adhesion to endothelium. (3) Exocytosis of gelatinase from gelatinase granules may help degradation of type IV collagen in basement membranes. (4) Mobilization of specific granules to the surface membrane may enhances the phagocytic potential of the neutrophils by providing CR3 (CD11b/CD18). Fusion of azurophil and specific granules with the phagosome creates conditions for oxygen-dependent and -independent bactericidal activity. (Modified and reprinted with permission.200 ).