Histochemical and immunohistochemical studies on keratan sulfate in the anterior segment of the developing human eye

Changes in the distribution of keratan sulfate in the anterior segment of developing ocular tissue were investigated histochemically and immunohistochemically using human eyes from 5 weeks gestation to 2 years after birth. Enzyme digestion methods with streptomyces hyaluronidase, chondroitinase and keratanase showed that the main component of glycosaminoglycans in the cornea was hyaluronic acid at the early stage and chondroitin sulfate from the middle stage to the neonatal stage. Keratan sulfate was found at the neonatal stage. Immunohistochemical staining, however, showed that keratan sulfate was present from 6 weeks around mesenchymal cells which migrated into the anterior portion. The stroma and endothelial cells of the cornea, trabecular tissue, iris, choroidal tissue of the ciliary body and anterior tunica vasculosa lentis were the next tissues to show positive for immunostaining. Keratan sulfate became limited to the cornea and lumbus and mostly disappeared from the other anterior segment tissues after birth. These findings suggest that tissues which seem to originate from mesenchymal cells and surround the chamber space contain keratan sulfate during the developmental stage.