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Figure 4 Hematoxylin and eosin (H&E) stain of tissue obtained from the subendocardial rim (A) and the remote zone (B) of mesenchymal stem cell (MSC)-treated animals. As shown, the rim of tissue is made up of cardiomyocytes with normal ultrastructural architecture. (C) There is no difference in the size of myocytes taken from the remote myocardium of both control and MSC hearts. However, the myocytes from the infarct rim are significantly smaller in MSC-treated animals versus control animals (n = 2 each, >100 cells/heart), suggesting that the enhanced rim size in MSC animals might be due to new cardiomyocyte regeneration. *p < 0.001 MSC rim versus control rim.