Figure 1.

SDF-1 promotes the survival of cultured embryonic chick RGCs, and its receptor CXCR4 is expressed in the embryonic retina. A, SDF-1 promotes the survival of RGCs in a dose-dependent manner. Shown are the percentages of surviving RGCs at 72 compared with 24 hr in the presence of 100 ng/ml selected chemokines or of 4 (p = 0.028), 20 (p = 0.008), or 100 ng/ml (p = 0.001) SDF-1. p values were calculated by comparing each population with the untreated one using a two-tailed test with different variances. B, Identification of RGCs in culture with anti-islet-1. C, Visualization of RGC neurons with an antibody to islet-1 in a cross section of an E6 chick embryo. The hash marks represent the ganglion cell layer. D, Visualization of CXCR4-expressing cells in the RGC layer of this same section by in situ hybridization. E, Merged image showing CXCR4 in all islet-1-positive cells.