Expression of TF in decidual tissue of aPL-treated mice. (A,B,D,E) Pregnant Balb/c mice were treated on day 8 with aPL-IgG or IgG from a nonautoimmune individual (NH-IgG) and killed 2 hours later. Uteri were dissected and decidua sections were cut. (A,B) Decidua sections stained with an anti–mouse TF antibody. The chromogen was DAB (brown) and the counterstain was hematoxylin. In aPL-treated mice (A), there was extensive TF staining (brown color) in deciduas (d) and embryo debris (ED). In contrast, the decidual tissue from NH-IgG–treated mice showed minimal staining for TF (B) at the ectoplacental cone (ec) (arrows) and intact embryo (E). Original magnification × 40. (C) TF levels in the uterine contents of aPL- and NH-IgG–treated mice were measured by Western blotting. Lane 1 shows purified mouse TF standard (3 μg); lane 2, uterine content of an aPL-treated mouse; lane 3, uterine content of a NH-IgG–treated mouse. (D,E) Immunohistochemical analysis of fibrin in sections of uteri from aPL-treated (D) and NH-IgG–treated (e) mice. Fibrin was detected only at the decidua-uterine wall interface (arrows), and no difference in the staining intensity was observed between the 2 treatments. Original magnification × 10. d indicates decidua; u, uterine wall.