Acidic and basic fibroblast growth factor (FGF) have been shown to be mitogenic for EC and pericytes, to stimulate angiogenesis in vivo and to induce the differentiation (neurite outgrowth) of retinal ganglion cells. The isolation of these factors from the retina strongly suggests a role for the FGFs in retinal development and vascularization. Under normal conditions retinal capillaries seldom proliferate. However, there are a number of retinopathies that are characterized by rapid new vessel growth. We have used heparin-affinity chromatography, antibodies specific for acidic and basic FGF, and cDNA probes levels to detect and quantify FGF by measuring: a) growth factors activity, b) protein levels and c) messenger RNA expression. Using these methods we propose: (1) to examine the time course and degree of FGF expression as well as its distribution in normal, developing and adult murine retina and in murine retinas with experimentally-induced retinopathy. Biochemical and immunocyto-chemical methods along with molecular and cell biological techniques will be used to analyze the distribution and expression of FGF, and (2) to investigate the biosynthesis, secretion and distribution of the FGFs and the modulation of their release in cultures of cells derived from normal retina including: EC, pericytes, glial cells and retinal pigment epithelial cells. Platelet-derived growth factor (PDGF) and transforming growth factor type beta (TGF-B) have also been shown to influence vascular cell proliferation. Using similar methods of detection and quantification, we propose: (3) to analyze the expression of TGF-B and PDGF in normal and abnormal, developing and adult murine retinas and in retina-derived cells in culture. To extend our understanding of endothelial growth control to the molecular level, we propose: (4) to analyze the regulation of EC growth by comparing gene expression and protein products bf FGF- stimulated EC to that of EC inhibited by TGF-B or by induction of tube formation in vitro. Our ultimate goal is to identify the mechanism(s) that underlie vascular growth control and determine how these controls are overridden, resulting in proliferative retinopathy.