Trichrome stains of wild-type and Pecam-1^−/−thrombi. Representative thrombus cross-sections of wild-type (A-D) and Pecam-1^−/− (E-H) mice on days 3 (A,E), 7 (B,F), 14 (C,G), and 28 (D,H) after vena cava ligation are shown. Initially, thrombi are fibrin-rich (red) and fragile, and subsequently become solid due to increased collagen synthesis (green). Scale bar, 100 μm.