Development of pulmonary vascular remodeling and neointimal lesions. A: Occlusion percentage of the intra-acinar vessels per experimental group (Materials and Methods). B: Muscularization per experimental group: percentage of intra-acinar vessels per degree of muscularization (including neointimal lesions). C: Typical examples (original magnification, ×400) of intra-acinar vessels per experimental group stained with Verhoeff. Note at M+F 30 the neointimal lesion with destruction of inner elastic membrane and disorganized cell proliferation. D: Typical examples of immunofluorescence double staining (original magnification, ×400) of intra-acinar vessels per experimental group: anti-SMA (red; smooth muscle cells), anti–von Willebrand factor (green; endothelial cells), and Dako (blue; nuclei). Note at M+F 30 luminal obstruction due to endothelial proliferation. Data are presented as mean ± SEM. *P < 0.05 versus controls. CON, pooled sham groups. Scale bar = 50 μm.