IN-SITU LOCALIZATION OF BASIC FIBROBLAST GROWTH-FACTOR PROTEIN AND MESSENGER-RNA IN THE RETINA

Basic fibroblast growth factor (FGF) protein has been recognized as a potent factor for angiogenesis and as a mitogen. The sites of basic FG F in the mammalian retina have varied from report to report. On the ot her hand, only the inner segments of the photoreceptor cells have been reported to synthesize basic FGF as revealed by the presence of mRNA for basic FGF by in situ hybridization. To define the sites of basic F GF and its mRNA in the human retina, we immunohistochemically localize d basic FGF protein and mRNA for basic FGF by in situ hybridization in normal human retinas. Basic FGF protein was found in the ganglion cel l layer, the inner and outer nuclear layers, and the basement membrane s of Muller cells (the inner limiting membrane), blood vessels, and th e retinal pigment epithelium (Bruch's membrane). The mRNA for basic FG F was found in the cells of the ganglion cell layer, the inner nuclear layer, and the outer nuclear layer, and the inner segments of the pho toreceptor cells. These findings suggest that basic FGF in the human r etina functions in both an autocrine as well as a paracrine fashion.