Extent of interstitial and periarteriolar fibrosis. (A,B) Representative images of picrosirius red-stained collagen fibers (bright red color) in the LV free wall myocardium of post-MI male and female rats. (C) Fractional volume of interstitial collagen fibers in the LV free wall and septum. (D) The content of periarteriolar collagen in the LV free wall and septum. Scale bars are 20 μm. Values are the mean ± SEM; n = 7 male rats/group; n = 6 female rats/group. A two-way ANOVA revealed a statistically significant interaction between the effects of sex and the experimental model on perivascular collagen content in both LV free wall, F (1, 22) = 6.860, P = 0.020, and the septum, F (1, 22) = 5.876, P = 0.028. *P < 0.05 vs. a corresponding sham group; §P < 0.05, §§P < 0.01, and §§§P < 0.001 vs. M-Sham; ††P < 0.01 and †††P < 0.001 vs. M-MI rats.