Fig. 10.

Histological images of the LV endocardial cross-sections (A) and (B) and LV myocardium cross-section (C) of the native porcine hearts showed that fine elastin fibers, along with collagen network, closely associated with the Purkinje cells, implying that this ECM association could be essential in organizing cardiac Purkinje cells into “fibrous” and “branching” morphologies. We noticed that the fine elastin fibers, meshing with collagen fibers, morphologically wrapped around groups of Purkinje cells (cell groups in cross-sectional view) (red arrows in A). Moreover, the fine elastin fiber arrays, which had local alignment, were also frequently observed scattering in-between the Purkinje cells, and those elastin fiber arrays always associating with yellow-stained collagen (blue arrows in B,C). We also captured the elastin fibers and collagen that were associated with subendocardial Purkinje fibers (A,B), the elastin fibers and collagen associated with the branch point from subendocardial Purkinje fibers (green arrow in B shows where T-shape branching happens), and the elastin fibers and collagen associated with the intramural Purkinje fibers (yellow arrow in C). Movat's pentachrome staining: Collagen in yellow, elastin fibers in black, cardiac muscles in red, and the Purkinje fibers in pale pink. Scale bar = 100 μm.