Expression of TF in decidual tissue and placentas from CBA/J × DBA/2 mice. (A) Deciduas sections from CBA/J × DBA/2 and CBA/J × BALB/c mice were harvested at day 7 of pregnancy, cut, and stained with anti–mouse TF. In CBA/J × DBA/2 mice (i), in approximately 30% of the conceptuses there was extensive TF staining in deciduas (d). In contrast, minimal TF staining in the mesometrial area (arrows) was observed in all the conceptuses in CBA/J × BALB/c mice (ii). Placentas collected at day 15 of pregnancy from CBA/J × DBA/2 mice (iii) showed massive TF staining (brown color) in the labyrinth (lab) and spongiotrophoblasts (sp) area, whereas placentas from control CBA/J × BALB/c matings showed minimal TF staining (iv). Deciduas from day-7 pregnant CBA/J × DBA/2 mice showed increased fibrin deposition (v) compared with CBA/J × BALB/c mating (vi). In CBA/J × DBA/2 mice, day-15 placentas showed robust fibrin deposition (brown color) in the labyrinth (lab) and spongiotrophoblasts (sp) area (vii), whereas placentas from control CBA/J × BALB/c matings showed minimal fibrin deposition (viii). Original magnification ×40. (B) Tissue factor staining in human placentas. Robust TF staining (green fluorescence) was observed in the villous trophoblast cells and basement membranes in placentas from IUGR neonates (iii,iv). In contrast, minimal TF staining was observed in placentas from uncomplicated pregnancies (i,ii). Original magnification ×10. (C) Placental blood perfusion was measured in CBA/J × DBA/2 and CBA/J × BALB/c mice after FITC-dextran (MW 2 000 000) injection in the maternal circulation. In control CBA/J × BALB/c matings with normal pregnancies, the fluorescent tracer accumulated in the placental labyrinth (i). Less blood perfusion was observed in the labyrinth of CBA/J × DBA/2 matings (ii). n = 6-8 mice/each experimental group. Four to 5 deciduas or placentas were studied in each experimental group.