Effect of fibrinogen on FGF-2-induced angiogenesis in Matrigel plugs in C57-BL6 mice. Matrigel supplemented with PBS (A), fibrinogen (500 μg/mL) (B), wtFGF-2 (500 ng/mL) (C), FGF-2 and fibrinogen (D), 2212 (E), 2212 plus fibrinogen (F), 221^*2 (G), or 221^*2 plus fibrinogen (H) was injected subcutaneously into C57BL/6 female mice. After 10 days, the Matrigel plugs were removed, fixed in 3% formalin, embedded in paraffin, sectioned, and stained with trichrome. Bar represents 100 μm. Top right panel: vessel growth was quantitated by counting the number of new vessels and branches and using image analysis software. Ten mice were used in each group. Data represent mean ± SEM. Bottom right panel: The hemoglobin content in Matrigel plugs removed at 10 days was measured using Drabkin reagent. Hemoglobin reflects the amount of blood in the plugs and provides an estimate of the amount of vascularization. Results are shown as mean ± SE.