Platelet presence alters BMDC recruitment to hypoxic tissues. Lethally irradiated WT mice were reconstituted with GFP BM. After tumor implantation (A-B) or hindlimb ischemia surgery (C-D), 3 × 10⁹ platelets were infused into mice every 5 days by tail vein injection (PLT Infusion, Treated). Control mice were injected with PBS (PLT Infusion, Control). Separately, mice were treated intravenously with 2 μg/g body weight rat antimouse GPIbα to deplete platelets (PLT Depletion, Treated) or rat IgG (PLT Depletion, Control). Injections were repeated every 3 days. (A-B) Subcutaneous B16-F10 tumors were removed after 9 days of growth. Tumors were sectioned and stained for blood vessels using a smooth muscle actin antibody (red) and 4,6-diamidino-2-phenylindole (blue). GFP⁺ BMDCs were counted per field. (C-D) Muscles were sectioned after 14 days of ischemia. GFP⁺ BMDCs were visualized by immunostaining (brown) and counted per field. Arrows indicate GFP⁺ cells. Scale bars represent 50 μm. Staining was quantified as mean GFP⁺ cells per field ± SEM (n = 5). *P < .05 vs control (Student t test). ***P < .005 vs control (Student t test).