Staining of FXII(a) and fibrin(ogen) in human carotid thrombi. Representative images of 3 human carotid thrombi. (A) Overall figure: H&E staining. (B) Immunohistochemical double staining for fibrin(ogen) and CD68 (staining for monocytes/macrophages). (C-D) Immunohistochemical double staining for FXII(a) and CD68 of a human carotid thrombus. (D) The FXII/FXIIa-positive and negative areas are outlined. Original magnifications: A, 2.5; B-C, 10; and D, 40.