Syntaxin 2 shows little colocalization with syntaxin I. A–C: Syntaxin 2 labeling is present in numerous amacrine cells (A) and small puncta throughout the inner plexiform layer (IPL; arrows and arrowheads). Syntaxin 1 is widely expressed in amacrine cell bodies, processes and presynaptic terminals. At low magnification, there is some apparent colocalization of these two syntaxin isoforms in conventional terminals (arrowheads), although many syntaxin 2-positive terminals do not show labeling for syntaxin 1 (arrowheads). Similarly, Most labeling for syntaxin 1 does not colocalize with labeling for syntaxin 2. Images shown from a projection of 13 optical sections with total thickness of 1.75 μm. D–F: Inspection at higher magnification shows that syntaxin 2 labeling is typically present in puncta that show little or no syntaxin 1 labeling, although a few puncta that show strong colocalization of labels are present (arrowheads). Colocalization associated with diffuse labeling, which is probably not associated with release sites, is also present. Images shown from a single optical plane. INL, inner nuclear layer, GCL, ganglion cell layer. Scale bars = 10 μm for A–C; 5 μm for D–F.