VIM-positive fibroblasts and TNC localize at the border zone between the myocardium and fibrotic tissue. (A, C, E and G) Heart sections immunostained for a cardiac nuclear marker MEF-2 (red) and an intermediate filament marker Vimentin (VIM, green). (B, D, F and H) Heart sections immunostained for a cardiac sarcomeric marker TPM (red) and an extracellular de-adhesive protein Tenascin-C (TNC, green). (A', B', C', D', E', F', G' and H') Higher magnifications of the framed area in the left panels. (A-A' and B-B') In control, at 4 days after sham operation, no significant expression of VIM and TNC can be detected in the ventricle. (C-C' and D-D') At 7 dpci, the scar margin and the interface between the myocardium and post-infarct are highlighted by VIM- and TNC-expressing fibroblasts. (E-E' and F- F') At 14 dpci, protrusions of cardiomyocytes expand along VIM/TNC-expressing cells (arrows). (G-G' and H-H') At 30 dpci, the scar tissue is largely replaced by cardiomyocytes. A new compact myocardial wall (arrowheads) surrounds residual VIM and TNC. Dashed line encircle the post-infarct. Bars in (A-A'), 300 μm.