Figure 3.

Blood vessel density is diminished upon platelet depletion. (A-D) Subcutaneous B16-F10 tumors were implanted in mice undergoing platelet (PLT) depletion or injected with control rat IgG. After 9 days of growth, tumors were excised and sectioned. (A-B) Tumor sections were stained for laminin to visualize blood vessels. Laminin-positive vessels were quantified and represented as mean vessel number per section ± SEM (n = 6). (C-D) Frozen tumor sections were stained for CD31-positive vessels (red) and DAPI (blue). CD31⁺ blood vessels were quantified and represented as mean percentage of area ± SEM (n = 24). Arrows indicate vessels within the tissues. (E-F) Platelets were depleted or infused in mice directly after hindlimb ischemia surgery. Muscles were collected from mice injected with 3 × 10⁹ platelets (PLT Infusion, Treated) or PBS (PLT Infusion, Control). Muscles were also collected from mice injected with rat anti–mouse GPIbα (PLT Depletion, Treated) or rat IgG (PLT Depletion, Control). Muscles were sectioned 14 days after surgery and immunostained for VWF positive blood vessels. Vessels positive for VWF were counted and represented as mean vessel number per field ± SEM (n = 5). Scale bars represent 50 μm. *P < .05 and ***P < .005 vs control by Student t test.