(A) Extension of trophoblast cell invasion was measured as the area of the mesometrial triangle invaded by trophoblast cells. This area was significantly increased in hAgt-targeting siRNA–treated (n = 9) preeclamptic (PE) rats compared with luciferase-targeting siRNA–treated (n = 10) rats (*P < 0.05; unpaired t test; mean ± SEM). (B) Representative pictures of cytokeratin-stained midsagittal mesometrial triangle (MT) and placental (P) tissue sections used to carry out the histomorphological analysis. Different zones of the placenta are marked: T, trophospongium; L, labyrinth. (C) The area of the mesometrial triangle was not different between luciferase-targeting siRNA– and hAGT-targeting siRNA–treated PE rats (mean ± SEM). (D) The overall size of the placenta was increased in hAgt-targeting siRNA–treated (n = 9) PE rats compared with luciferase-targeting siRNA–treated (n = 10) rats (*P < 0.05; unpaired t test; mean ± SEM). (E) The area of the trophospongium was not changed in hAgt-targeting siRNA–treated (n = 9) PE rats compared with luciferase-targeting siRNA–treated (n = 10) rats (mean ± SEM). (F) The area of the labyrinth zone of placentas of hAgt-targeting siRNA–treated (n = 9) PE rats was enhanced in comparison with luciferase-targeting siRNA–treated (n = 10) rats (*P < 0.05; unpaired t test; mean ± SEM). (G) Representative pictures of CD68-stained uteroplacental unit tissue sections. (H) The number of macrophages was increased in hAgt-targeting siRNA–treated (n = 9) PE rats compared with luciferase-targeting siRNA–treated (n = 9) rats. **P < 0.01; unpaired t test.