LOCALIZATION OF ALPHA(2,3) AND ALPHA(2,6) LINKED TERMINAL SIALIC-ACIDGROUPS IN HUMAN TRABECULAR MESHWORK

Sialic acid specific lectins were used to localise isomers of sialyl g lycosides in human trabecular meshwork (TM) at the ultrastructural lev el. A lectin immunogold method demonstrated that sialic groups were co ncentrated on the endothelial surface of Schlemm's canal (SC) and in t he adjacent juxtacanalicular tissue (JCT). One sialyl glycoside, alpha (2,6) linked N-acetyl neuraminic acid, was present mainly on the lumin al aspect of the SC endothelium and in the cytoplasm of the JCT cells. Another, alpha(2,3) linked N-acetyl neuraminic acid, was localised pr edominantly to the extracellular fibrillar material of the JCT. The ex istence of a topographical segregation of these two sialyl glycosides within the TM supports the view that highly charged anionic molecules may be of significance in regulating aqueous outflow.