TIME-COURSE EXPRESSION OF VASCULAR ENDOTHELIAL GROWTH-FACTOR AS RELATED TO THE DEVELOPMENT OF THE RETINOCHOROIDAL VASCULATURE IN RATS

Growth factors involved in angiogenesis are critical to both the norma l and pathological vascular development in the retina and choroid. In the present experiment, the relationship between the vascular endothel ial growth factor (VEGF) expression and the retinochoroidal vasculogen esis in Sprague-Dawley rats was investigated using in situ hybridizati on and immunohistochemistry. It was found that VEGF was produced mainl y by astrocytes and Muller cells in the neural retina, and this was co rrelated temporally and spatially with the retinal vasculogenesis. In addition, it was observed that, although the VEGF expression in the re tinal pigment epithelium (RPE) decreased with increasing age, it persi sted from the embryonic stage to adulthood. These findings indicate th at the VEGF expression in RPE may play a role in the development of th e choroidal vessels as well as in the maintenance of the normal struct ure and permeability of the choriocapillaris in adults.