GLYCOSAMINOGLYCAN AND COLLAGEN DISTRIBUTION IN THE DEVELOPING HUMAN VITREOUS

Background: We determined the distribution of glycosaminoglycans and c ollagens in the developing human vitreous. Methods: Eighty human eyes from 5 gestational weeks to 2 postnatal years of age were used. Glycos aminoglycan components were determined by enzyme digestion with hyalur onidase or chondroitinase AC and ABC and immunohistochemistry for chon droitin, chondroitin-4-sulfate, chondroitin-6-sulfate, and dermatan su lfate. Collagen distribution was determined by immunohistochemistry fo r types I, II, and III collagens. a Results: Enzyme digestion showed t hat throughout development hyaluronic acid is the main glycosaminoglyc an in the vitreous and in the extraocular space at 5-7 gestational wee ks. Both areas were filled with mesenchymal cells. Immunohistochemistr y showed chondroitin-6-sulfate in the vitreous between 6 and 40 gestat ional weeks, and chondroitin-4-sulfate between 12 and 40 gestational w eeks. Hyaluronic acid and chondroitin sulfate appeared in the retina a nd around the hyaloid vessels at 12-40 weeks. Immunohistochemistry sho wed type III collagen in the vitreous and around the mesenchymal cells at 5-7 weeks that was replaced by type II collagen after 8 weeks. Con clusions: Hyaluronic acid is the major glycosaminoglycan in the vitreo us throughout development, except for the transient appearance of chon droitin sulfate at 6-40 gestational weeks. Type III is the main collag en in the early developing vitreous that converts to type II collagen at 8 weeks. The primary and secondary vitreous has the same components as these macromolecules. These vitreous glycosaminoglycans and collag ens seem to be produced by mesenchymal cells at an early stage and by the retina and hyaloid vessels during middle and late development.