The Elastin Fiber System Between and Adjacent to Collector Channels in the Human Juxtacanalicular Tissue

Purpose: To determine the composition and investigate the elastin fiber system in the juxtacanalicular tissue adjacent to and between collector channel orifices in normal human eyes.

Methods: Normal human eyes (71.0 ± 8.6 years; mean ± SD; n = 4) were perfusion fixed at low (10 mm Hg) and high pressure (20 mm Hg) with 3% paraformaldehyde/0.1 M phosphate buffer. Frontal serial sections were cut from paraffin blocks, and regions with and without collector channels were selected. Sections were stained using Weigert's resorcin-fuchsin stain with oxidation. Immunohistochemistry was performed using antibodies against elastin, fibrillin-1, and microfibrillar-associated protein-1/2.

Results: Elastin, elaunin, and oxytalan fibers were identified within the juxtacanalicular tissue of the inner and outer walls in low- and high-pressure eyes. These fibers were found at collector channel orifices, between collector channels, and within collector channel walls. Fibrillin-1 was located at the base and lateral edges of Schlemm's canal endothelial cells. Microfibrillar-associated protein-1/2 was found with elastin-like fibers at the base of Schlemm's canal endothelium cells, in the juxtacanalicular tissue, and in the uveal region.

Conclusions: Elastin, elaunin, oxytalan, and elastin-associated proteins fibrillin-1 and microfibrillar-associated protein-1/2 were identified within the juxtacanalicular tissue of the inner and outer walls and within collector channel walls of human eyes perfused at low and high pressure. No differences in labeling patterns for elastin, elaunin, and oxytalan were found in the juxtacanalicular tissue adjacent to or between collector channel orifices. The elastin fiber system appears to have a significant role in the support and distensibility of the juxtacanalicular region under collector channels.