Fig. 4.

Identification and quantification of retinal ganglion cells (RGC) and amacrine cells with BDNF expression in the ganglion cell layer (GCL) of E15 chick embryos (A–C) and quantification of BDNF mRNA in the retina after degeneration of RGC induced by optic stalk transection (D). A, Section through the retina retrogradely labeled with Microruby (white grains) and hybridized for BDNF mRNA (dark silver grains). Note that many RGC are retrogradely labeled (thin arrows), but most of the BDNF-expressing cells (large arrow) are not fluorescent. Not all Microruby grains are in the focus plane. Scale bar, 20 μm. B, Comparison of the percentage of Microruby-labeled cells (RGC) in the GCL before and after hybridization. Note that there is no apparent quenching of the fluorescent signal. The number of visual fields (with ∼70 cells each) analyzed is indicated within white squares. Error bars indicate SEM. C, Percentages of BDNF-expressing cells for the RGC population (identified by labeling with Microruby) and for the amacrine cells (AMA; identified by the lack of fluorescent label). Note that <3% of RGC express BDNF, as compared with ≈15% of BDNF-expressing amacrine cells in the GCL. The number of visual fields analyzed (with a total of 392 cells) is indicated withinwhite squares. Error bars indicate SEM.D, BDNF mRNA was measured at age E17 by quantitative RT-PCR in normal retinae (Control) and compared with retinae lacking most RGC (Transected). BDNF mRNA levels were not reduced significantly in retinae after the destruction of their RGC. Error bars indicate SEM. Similar data were obtained for retinae from age E14.