Figure 12.

Hematoxylin and eosin–stained micrographs demonstrating the presence of microspheres (asterisks) in the lumen of functional microvessels accompanying the viable cardiac myocytes in 4-week-old (A, B), 8-week-old (C, D), and 12-week-old (E, F) transmural post-MI scars. The clusters of cardiac myocytes surviving in subepicardial (A, C, E) and subendocardial (B, D, F) regions of the corresponding scars are outlined by the black dotted lines. In micrographs B, D, and F, arrows point to the endocardium, whereas in micrographs C and E, veins are indicated by V and an artery by A. It is important to emphasize that the presence of microspheres in microcirculatory beds associated with the viable cardiac myocyte suggest their functional potency. Moreover, structural appearance of a majority of thin-walled microsphere-containing microvessels points at their venous origin. Scale bar is 30 µm (A–F). Abbreviation: MI, myocardial infarction.