Fig. 3. Localization of Barhl2 protein in postmitotic amacrine, horizontal and ganglion cells. (A) Retinal sections from BrdU-labeled E17.5 embryos were double-immunostained with antibodies against Barhl2 (red) and BrdU (green). Barhl2-immunoreactive cells, even those within the outer neuroblastic layer (indicated by arrowheads), do not overlap the S-phase cells immunoreactive for BrdU. (B-I) Double-immunolabeling of adult retinal sections using an anti-Barhl2 antibody and antibodies against several indicated cell type-specific marker proteins. Barhl2 appears to be expressed in all amacrine cells immunoreactive for syntaxin (B), glycine transporter 1 (GLYT1) (C), GABA receptor GABA_B (D), calretinin (E) and calbindin D-28k (F); and in all horizontal cells immunoreactive for calbindin (F), but only in a subset of ganglion cells immunoreactive for Brn3a (G). By contrast, Barhl2 is absent from rod bipolar and Müller cells immunoreactive for protein kinase C (PKC) and glutamine synthase (GS), respectively (H,I). Arrows indicate representative colocalized cells. GCL, ganglion cell layer; INL, inner nuclear layer; IPL, inner plexiform layer; onbl, outer neuroblastic layer; ONL, outer nuclear layer; OPL, outer plexiform layer. Scale bar: 10 µm in A-F,H,I; 16.7 µm in G.