Disruption of iridial blood-aqueous barrier in experimental diabetic rats.

The permeability pattern of iridial blood-aqueous barrier in streptozotocin-diabetic rats, maintained for 1-6 months, was studied with the light and electron microscopes, using horseradish peroxidase as a tracer. A reaction product of horseradish peroxidase was confined to the vascular lumina and to a small number of vesicles on the luminal portion of the endothelial cells in control rats and diabetic rats maintained for 1 month. In diabetic rats maintained for 2-6 months, endothelial cells contained a large number of horseradish peroxidase-labeled vesicles which opened into the basement membrane, and intercellular junctions of the endothelial cells were filled with horseradish peroxidase. Horseradish peroxidase was consistently found in the stroma around the vessels, and seemed to reach the anterior chamber through the intercellular spaces between the fibroblasts. However, the passage of horseradish peroxidase was blocked by the posterior epithelial cells.