Spleen platelet accumulation. Fluorescent platelets from wild-type or from P-sel^−/− mice were injected in the tail vein of wild-type synergic mice. Animals were killed 24 hours after platelet injection and their spleens retrieved, fixed, and included in optimal cutting temperature medium. Fluorescent platelets in the tissue were then revealed by confocal microscopy. See text for experimental details. (A) Mice injected with wild-type resting platelets. (B) Mice injected with wild-type activated platelets. (C) Mice injected with P-sel^−/− activated platelets.