E2 restores RV function and reverses RV fibrosis associated with pulmonary hypertension (PH). A: RV pressure in CTRL, RVF, and E2. B: trichrome staining of RV cross sections. Red indicates cardiomyocytes and blue shows collagen deposition (fibrosis). C: quantification of %RV fibrosis in CTRL, RVF, and E2. D and E: RV lysil oxidase (D) and collagen I relative transcript expression (E) in CTRL, RVF, and E2. **P < 0.05 vs. CTRL; ##P < 0.05 vs. RVF.