Elevated fibrinogen increases fibrin(ogen) incorporation into thrombi after FeCl3 injury. Representative sections through thrombi after FeCl3 injury to the carotid artery (A) or saphenous vein (B). Hematoxylin and eosin staining shows regions of protein and packed erythrocytes. Immunohistochemistry (IHC) for fibrin (59D8) on corresponding sections shows darker staining for fibrin(ogen) at the thrombi margins and in thrombi from hyperfibrinogenemic (170% fibrinogen) mice. “No 1° Ab” indicates antibody 59D8 was omitted from IHC as a negative control. Staining intensity (on a scale of 0-3) was normalized to assign the value of 3 to the most intensely stained section in each vessel separately. Mean staining intensity from immunohistochemistry images from 3 separate carotid arteries (C) or 4 separate saphenous veins (D) for each condition was determined as described in “Hematoxylin and eosin staining and immunohistochemistry” and compared with control (wild-type) carotid artery (P = .1) and saphenous vein, respectively. *P < .05.