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. 2018 May;15(5):752–760. doi: 10.1016/j.hrthm.2017.12.027

Figure 2.

Figure 2

Masson's trichome staining. Proximal penetrating bundle (PPB) in young and old hearts. A–C: Sections at the PPB level at different magnifications in a young heart. E–G: Comparable images in an old heart. PPB is marked with a black dotted line. Pink/purple indicates myocytes and black blue indicates nuclei in high-magnification images (panels C and G). LA = left atrium; LV = left ventricle; RA = right atrium; RV = right ventricle. Bar is shown in each image. Red seen in panel A indicates clotted blood. Panels C and G showed disruption in cellular architecture seen with aging. D: Number of nuclei measured in high-magnification images in the regions of the atrioventricular junction. H: Collagen signal estimation in young and old hearts' atrioventricular junction measured by Picrosirius red staining and polarized microscopy. CN = compact node; DPB/His = distal penetrating bundle or His bundle; PPB = proximal penetrating bundle. Young hearts, n = 6; old hearts, n = 6. ∗ P < .05.