[Demonstration of glycosaminoglycans (GAGs) in fetal human trabecular tissue]

The ultrastructural localization of glycosaminoglycans (GAGs) in the developing human outflow apparatus was investigated. The aqueous outflow system from human eyes at 26th and 36th fetal week and 2 years of age was stained with ruthenium red to identify GAGs with the transmission electron microscope. Luminal surface of the inner wall of the Schlemm's canal, basal lamina of the endothelial cells, basal lamina-like material, amorphous substances and collagen fibrils in juxta-canalicular tissue were associated with ruthenium red-stainable material. The basal lamina of the endothelial cells of Schlemm's canal was stained less obviously in 2-year-old trabecular tissue. The composition of the ruthenium red-stainable material was determined by treatment of each tissue with streptomyces hyaluronidase, chondroitinase AC, and chondroitinase ABC respectively. Hyaluronic acid was identified in each ruthenium red-stainable extracellular component. Chondroitin sulfate was identified in all ruthenium red-stainable components except luminal surface of the canal. The presence of dermatan sulfate was confirmed in the amorphous components and collagen fibrils of juxta-canalicular tissue. The results suggest that GAGs in fetal trabecular tissue already contribute to the outflow resistance and that alterations of the pattern of GAGs may take place as development proceeds.