Figure 1.

Transverse sections of cardiac muscle, illustrating multiple levels of structural heterogeneity. (a) Components of the extracellular space, including capillaries (X_bv), empty space (X_e), connective tissue (X_f) and collagen (X_c), embedded in ground substance (X_g). Scale bar, 1 μm; Ncl, nucleus (7500×). Reproduced with permission from [5]. (b) Distribution of microvasculature in canine ventricular muscle (arrows), producing multiple indentations along the perimeter of each myocyte. The markedly heterogeneous distribution of interstitial space surrounding capillaries and myocytes is also appreciated. Left bar, 50 μm; right bar, 10 μm. Reproduced with permission from [6].