Figure 1. Specimen preparation and orientation.
A, intact rat heart with sample tissue location indicated, and pulmonary artery (PA) cannulated. The right ventricle is delineated with blue beads, the outflow tract (OT) region with black beads and the right ventricular apical region (Apex) with red beads. The rectangle indicates the selection of the tissue samples; X1: apex-to-outflow-tract (preferred) direction; X2: cross-preferred direction. B, example of a full-thick RVFW specimen; the four blue markers delineate the region of structural and mechanical analysis. C, histological section (25 μm thickness) of the midwall RVFW stained with Masson's trichrome. The section shown is 400 μm from the endocardial surface and shows strong preferred myofibre alignment along the apex-to-outflow tract direction (X1 direction).