Fig. 6

Histopathologic evaluation of reperfused and non-reperfused myocardial infarct (MI). Representative triphenyltetrazolium-chloride (TTC)-stained heart slices and histopathologic samples are shown. TTC slices were prepared from the same animals as shown previously (see Fig. 4) and the slices correspond to the magnetic resonance imaging (MRI) slices shown above. The visual TTC assessment of the MI in the reperfused model (a) shows a remarkable central brown region indicating the presence of a significant amount of blood (formaldehyde turns blood brown). TTC in the non-reperfused model (b), however, shows the entire MI as a nearly homogenous unstained area. The microspheres used for generating the occlusion in the non-reperfused model can be clearly seen by the naked eye (b) (green rectangle). The microsphere (c) (green star) (H&E × 10 magnification) is entrapped in a small epicardial branch of the left circumflex (LCX) coronary artery and the remaining lumen of the vessel is filled with thrombi and blood cell remnants (c) (green circle). MI regions were further evaluated using H&E (d, e) (×20 magnification), Prussian blue (g, h) (×20 magnification), and Von Kossa (j, k) (×20 magnification) staining; black rectangles and blue rectangles indicate the sampled regions as shown in a, b, respectively). Details are provided in Results. Normal myocardial tissue (red rectangle shows sampling region (b)) stained using H&E, Prussian blue and Von Kossa staining (f, i, l) is displayed for comparison