Abstract
Purpose: :
Elastin and elastin-like fibers are essential to the resiliency of the trabecular meshwork extracellular matrix. However, the exact makeup of the elastin-like fibers in the trabecular meshwork has not been fully elucidated. In this study, we determined if oxytalan and elaunin fibers, members of the elastin fiber system, are present in the juxtacanalicular region (JCT) of the trabecular meshwork.
Methods: :
Normal aged human eyes (66.5 ± 6.4; mean ± SD; n=4) with pigmented irises were perfusion fixed with 4% paraformaldehyde/0.1M phosphate buffer. Two quadrants from each eye were processed for paraffin sectioning and light microscopy. Seven micron serial sections in a frontal orientation were used to select regions with and without collector channels. Sections were stained using Weigert’s Resorcin-Fuchsin with and without oxidation. Weigert’s Resourcin-Fuchsin with oxidation stains elastin (black), elaunin (dark lavender), and oxytalan fibers (light lavender). Human skin was used as a positive control.
Results: :
In the JCT, elastin fibers run parallel and obliquely to the inner wall of Schlemm’s canal. Elaunin fibers extend from elastin fibers at ninety degree angles towards Schlemm’s canal and continue to the base and lateral edges of Schlemm’s canal endothelium. Oxytalan fibers were found extending from elaunin fibers and terminating at the base of Schlemm’s canal endothelium. In expanded JCT regions underneath collector channels, elaunin and oxytalan fibers appeared as long and straight fibers, perhaps being stretched from JCT cell to JCT cell.
Conclusions: :
Elaunin, oxytalan, and elastin fibers are present in the trabecular meshwork JCT region in areas with and without collector channels. Further investigation analyzing interactions of the elastin fiber system with Schlemm’s canal endothelial cells and extracellular matrix in normal and glaucomatous eyes is warranted.
Keywords: trabecular meshwork • anatomy • microscopy: light/fluorescence/immunohistochemistry