Fig. 2. In situ hybridization for subsets of genes reveals that these genes depend on Brn3b for expression in the retina through both cell-autonomous and non-cell-autonomous mechanisms. DIG-labeled probes for individual genes were hybridized to E14.5 Brn3b heterozygous (+/-) and null (-/-) sections across the eye. (A) Consistent with the microarray results, expression of the RGC-specific neurofilament 66 gene (Nf66) was not dependent on Brn3b. (B) Two examples, Dlx1 and cyclin D1 (Clnd1), whose expression did not coincide with Brn3b but was affected by the absence of Brn3b. In the heterozygous retina, both Dlx1 and cyclin D1 were expressed mostly in the progenitor cell layer. In the Brn3b^-/- retina, Dlx1 was upregulated, most prominently in the RGCs, while cyclin D1 was downregulated. (C) Five examples RGC-specific genes downregulated in the absence of Brn3b: Gap43, synaptotagmin 13 (Syt13), neurofilament light-chain gene (Nfl), Hermes and myostatin/Gdf8.