Fig. 1.

Masson trichrome and discoidin domain receptor-2 staining in adult and aged ventricles. A: low-power magnification of the entire cross-sectional view of an adult and aged rat hearts. Notice the increased fibrosis in the aged (blue stain) with almost complete fibrosis at the endocardium (Endo) and diffuse fibrosis of the posterior left ventricle (LV) and the septum. B: overall percent area of fibrosis in adult and aged ventricles. C and D: regional variations of percent fibrosis at 14 different ventricular sites. E: trichrome stain that stains collagen blue. F: discoidin domain receptor 2 that stains the fibroblast in green. G: trichrome stain in adult (left) and middle-aged rabbits (middle and right) in which H₂O₂ induced spontaneous ventricular fibrillation (VF). Ant, anterior; RV, right ventricle; Post, posterior; Epi, epicardium; NS, not significant.