Figure 3.

Distribution of surviving cardiac myocytes in a representative 12-week-old transmural post-MI scar visualized by double immunofluorescence staining with antibodies against cardiac MHC β-isoform (red color) and laminin (green color). In all micrographs, nuclei are counterstained with DAPI (blue color). (A) Low-power view of the scar demonstrating the discontinuous layers of viable cardiac myocytes beneath the endocardium (arrows) and epicardium (white dotted line). Note that viable cardiac myocytes are present around a large vein (V), whereas they are completely absent in the vicinity of coronary arteries (A). (B) High-power view of the subepicardial region outlined by the white box in A showing the viable cardiac myocytes beneath the epicardium (white dotted line) and around the large subepicardial vein (V). (C) High-power view of the subendocardial region outlined by a white box in A demonstrating the viable cardiac myocytes beneath the endocardium. Scale bars are 100 µm (A) and 50 µm (B, C). Abbreviations: MI, myocardial infarction; MHC, myosin heavy chain; DAPI, 4′,6-diamidino-2-phenylindole.