Localization of acid-washed fibrin/fibrinogen in the murine pulmonary vasculature. PLP-fixed cryosections of mouse lung were acid washed to solubilize fibrinogen and fibrin degradation products before immunolocalization with an anti-fibrin/fibrinogen IgG and counterstaining with hematoxylin. Wild-type (TM^+/+) mice between 15 and 20 months of age display little or no immunoreactivity at the intimal surface (representative image shown in a), whereas age-matched TM^−/− chimeric (Ch TM) mice display a strong cross-linked fibrin immunolocalization at the lumenal surface of blood vessels (b). Endothelial cell nuclei are indicated by arrowheads. Original magnification × 400.