Morphological study on glycosaminoglycans in the developing human vitreous

The vascular and the avascular vitreous in 7th- and 8th-week human embryos and 9th-week fetuses were stained strongly by alcian blue, while marked decrease in staining by alcian blue was observed in 12th- and 13th-week human fetuses. The nature of alcian blue positive materials was identified as hyaluronic acid and chondroitin sulfate or dermatan sulfate by enzymatic digestion methods and the Scott-Dorling method. The results suggest that distinction between primary and secondary vitreous is difficult by classical histochemical techniques and electron microscopy, and that the vitreous glycosaminoglycans concentration seems to be high at 7th- and 8th-week embyonic stages and decreases at later fetal stages.