Permeability pattern of retinal capillaries in streptozotocin-diabetic rats, maintained for 1-6 months, was studied with the electron microscope, using horseradish peroxidase as a tracer. A reaction product of horseradish peroxidase was confined to the capillary 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, reaction product was observed in the basement membrane of endothelial cells and pericytes and extended to the extracellular spaces around the capillaries. The number of reaction product-labeled vesicles in the capillary endothelial cells was greatly increased in diabetic rats maintained for 2 months, as compared with that in control rats and diabetic rats maintained for 1 month. Reaction product was also found in the intercellular junctions of capillary endothelial cells from the luminal to the abluminal portion in diabetic rats maintained for 3-6 months. The increased permeability in retinal capillaries of diabetic rats preceded the thickening of the basement membrane, and seemed to play an important role in the development of diabetic retinopathy.
All Science Journal Classification (ASJC) codes
- Sensory Systems
- Cellular and Molecular Neuroscience