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Purpose: To investigate the effect of intravitreal basic fibroblast growth factor(bFGF) on activation and proliferation of endogenous retinal progenitor cells in the Royal College of Surgeons(RCS) rats., Methods: Twenty-four rats were studied after the 30th postnatal day(≥30). Eighteen affected rats were randomly divided into 3 groups: bFGF-treated, vehicle-treated and untreated group, and 6 unaffected rats were used as normal controls. Six μl of bFGF (5μg/10 μl) or vehicle was injected into the vitreous on days 31, 33 and 35 after birth (P31, P33, P35) in the bFGF group and vehicle group, and no injection was administered in the untreated and control groups. All the rats were euthanized, and their eyes were enucleated, hemisected and fixed at 50 d after birth for immunohistochemistry and measurement of outer nuclear layer thickness., Results: Nestin and Chx10 were positively expressed in all retinal layers, intravitreous injection of bFGF in retina-dystrophic RCS(RCS-p+/Lav) rats induced intense labeling for the retinal progenitor cell markers Chx10 and Nestin, which were highly colocalized. Fluorescence intensity for both labels was slightly less in the control rats, and much less in the vehicle-injected rats as well as in the untreated RCS rats. The outer nuclear layer (ONL) was significantly thicker in bFGF group than that of vehicle-treated or untreated group(p<0.01), but thinner than that of the control group(p<0.01). No significant difference was observed in the ONL thicknesses between the vehicle group and untreated group(P>0.05)., Conclusion: bFGF may contribute to the activation of retinal progenitor cells in RCS rats, thus counteract degeneration by promoting the proliferation of the progenitor cells.