In situ localization of basic fibroblast growth factor protein and mRNA 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 FGF in the mammalian retina have varied from report to report. On the other hand, only the inner segments of the photoreceptor cells have been reported to synthesized basic FGF as revealed by the presence of mRNA for basic FGF by in situ hybridization. To define the sites of basic FGF and its mRNA in the human retina, we immunohistochemically localized basic FGF protein and mRNA for basic FGF by in situ hybridization in normal human retinas. Basic FGF protein was found in the ganglion cell layer, the inner and outer nuclear layers, and the basement membranes of Müller cells (the inner limiting membrane), blood vessels, and the retinal pigment epithelium (Bruch's membrane). The mRNA for basic FGF 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 photoreceptor cells. These findings suggest that basic FGF in the human retina functions in both an autocrine as well as a paracrine fashion.