Figure 3.

Collagen Alignment as Visualized by Picrosirius Red Staining With Polarized Light Microscopy

(A) Schematic representation of a longitudinal section of the valve leaflet with the respective regions indicated in the leaflet image collection, with radial and circumferential directions as indicated. (B) Collagen alignment in the native sheep pulmonary valve leaflet for reference, revealing the 3-layered structure with the fibrosa (f), spongiosa (s), and ventricularis (v). Circumferentially aligned fibers are oriented perpendicular to the field of view, appearing as speckle-like structures. Radially aligned fibers are oriented parallel to the field of view, appearing as fiber-like structures. (C and D) Representative images of collagen alignment in the hinge, belly, and tip regions of 12-month explantation in the (C) rTEHV and (D) aTEHV groups. Scale bars, 100 μm. Abbreviations as in Figure 2.