Fig. 3

Evaluation of pulmonary arterial remodeling in severe PAH rats. a-c Remodeling of rat pulmonary arteries (less than 50 μm in diameter) after chronic hypoxia (Hx), after monocrotaline treatment (MCT), or in rats treated with MCT and exposed to 4 weeks of Hx (MCT + Hx), compared to control rats (CTRL). a Representative cross-sectional views of remodeled pulmonary microarteries (1: CTRL; 2: Hx; 3: MCT; 4: MCT + Hx) showing medial thickening and luminal occlusion (van Gieson staining). b Percentage of medial thickness. c Luminal occlusion score. For b) and c), results are presented as means ± SEM with n = 7–11 rats per group. Determination of statistically significant differences was assessed with a one-way analysis of variance followed by a Dunn test. **p < 0.01 and ***p < 0.001 versus control. ^## p < 0.01 versus Hx. For a) scale bars represent 10 μm. d Representative cross-sectional views of lesions observed in small pulmonary arteries of rats treated with MCT and exposed to 4 weeks of Hx. 1–5: pulmonary arterial plexiform-like lesions (stalk-like lesions) (1: picro-Mallory staining; 2–5: hematoxylin and eosin staining). 6: pulmonary arterial thrombotic lesion (Picro-Mallory staining). 7: pulmonary arterial eccentric lesion (hematoxylin and eosin staining). 8–11: concentric cellular neointimal lesions in pulmonary microarteries (8: hematoxylin and eosin staining, 9: α-smooth muscle actin and 10–11: von Willebrand factor immunostainings). Scale bars represent 20 μm