Ultrastructural immunocytochemical localization of elastin in normal human trabecular meshwork.

Previous studies have suggested that hydrophobic moieties within the aqueous outflow channels might interact with certain aqueous components to retard outflow. While elastin is among the most hydrophobic proteins in the trabecular meshwork, it reacts poorly with conventional ultrastructural staining methods, so its potential role in regulating outflow could not be assessed. It was our goal to specifically localize elastin ultrastructurally using polyclonal antibodies against alpha elastin and its soluble precursor, tropoelastin. Human aorta served as a positive control. Preadsorption of the primary antibodies or their substitution with either normal rabbit serum or Tris buffer resulted in negligible labelling. With either antibody, only the electron-lucent elements in the center of elastic fibers of the trabecular meshwork were labelled, indicating that only these elements truly represent elastin. The pattern of elastin distribution within these fibers is most consistent with that found in tendons elsewhere in the body.