5.3 Retinal Cell Types that Produce VEGF
The retina contains two types of glial cells: macroglia and microglia. The Müller cell is the most common macroglial cell type and is unique to the retina. Shaped like a spindle, Müller cells expand across the entire retina. Müeller cells are thought to have a key role in the pathogenesis of retinal microangiopathy in the diabetic eye because they produce factors that regulate blood flow, cell survival, and vascular permeability, and their processes surround all blood vessels in the retina. The astrocyte is the less common type of macroglial cell. As it develops, the astrocyte travels along the optic nerve to reach the retina. Astrocytes form a monolayer at the inner limiting membrane. In vivo laboratory data have shown that astrocyte connexin-26 and -43 gene and protein expression decreases after 4 weeks of experimentally-induced diabetes and before significant astrocyte loss. During this same time period the retina became hypoxic. These data suggest astrocytes could play a key role in changes in retinal vasculature and inner retinal dysfunction in diabetes.
Quiz Module 5.3
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1. What is the hallmark of proliferative retinopathy?
2. What factors precipitate retinal neovascularization?
3. What are some retinal cell types that synthesize VEGF?
4. True or False: VEGF is an important link between the neurodegenerative process that occurs in early stages of diabetic retinopathy and the breakdown of the BRB.