[Proteoglycan molecules in scleral tissue of enlarged eyeball]

We studied scleral specimens from experimentally induced enlarged eyeball with axial elongation by the transmission electron microscopy following cationic dye (cuplonic blue) staining. The animal model was prepared by the injection of alpha-chymotrypsin into the posterior chamber of young albino rabbits. Cuprolinic blue staining was applied to scleral specimens obtained from equatorial lesion and portions of the scleral tissues were subjected to enzyme digestion by chondroitinase ABC, AC and B before cuprolinic blue staining. In control eyes, dermatan and chondroitin type sulfated proteoglycan filaments were identified. Large, electron dense, and abnormal by shaped proteoglycan filaments were seen in the transmission electron microscopy. Such abnormal proteoglycan filaments were susceptible to enzyme chondroitinase ABC and AC digestion but resistant to chondroitinase B, suggesting that they are chondroitin sulfate dominant proteoglycans. Our morphological data corroborated a previous biochemical report of abnormally induced proteoglycan molecules in sclera with enlarged, axially elongated eyes.