FIG. 12.

Discontinuous structure of the myocardium. Panel (a): Reconstructed volume of rat left myocardium shows complex arrangement of cleavage with each layer being 80 μm in thickness. Reproduced with permission from D. A. Hooks et al., Circ. Res. 91, 4 (2002). Copyright 2002 Wolters Kluwer Health, Inc.⁹¹ Panel (b): Connective tissue sheets separating human myocardial muscle bundles in atrial pectinate muscle. These connective tissue sheets are typically found in tissue from aged but not from young individuals. Reproduced with permission from M. S. Spach et al., Circ. Res. 58, 3 (1986). Copyright 1986 Wolters Kluwer Health, Inc.⁷⁶