Structural organization of collagen fibers in chordae tendineae as assessed by optical anisotropic properties and Fast Fourier transform

The structural and supraorganizational arrangement of the chordae tendineae components is very important for a better understanding of their morphophysiological relationships. This study aims to evaluate the degree of statistical variability of the distribution and orientation of collagen fibers and their undulations (crimps), in porcine chordae tendineae. Polarization microscopy, in association with image analysis, was used for the analysis of birefringent images and detection of surface plots, Fast Fourier transforms, and form birefringence curve profiles. A marked variability in the collagen fiber’s twisted and intertwined orientation was found not only along the long axis of the chordae tendineae but also in their 3-D structure, including that of the crimp structures. Crimp was demonstrated to not represent a homogeneous distribution of bands; the best methods to quantify its variability were the Fast Fourier transform and the line profile extended along the long axis of the chordae tendineae. Collagen fiber rings, considered to possibly protecting the integrity of the chordae tendineae, were observed to wrap around them. A statistically helical structure is assumed for the supraorganization of the collagen fibers in the chordae tendineae, which is suggested here to be a chiral body.