Plasma protein accessibility to the core region is limited. Photomicrographs showing representative hemostatic plugs from 2 different mice. (A) The anti-P-selectin antibody was infused prior to injury and circulating throughout hemostatic plug formation. (B) The anti-P-selectin antibody was infused 25 minutes post-injury. For both A and B, the platelet (i) and P-selectin (ii) channels are shown individually as gray-scale images and the merged image (iii) is shown in color (red, platelets; green, P-selectin). Bars represent 10 µm. A line drawing of the merged images is included for clarity (iv). Note that the P-selectin antibody is unable to penetrate the core region when infused 25 minutes post-injury.