Fig 2: Vertical cryosections of the retinas of adeno-associated virus (AAV)-transduced (left column) and untreated control animals (right column) with antibodies against different outer plexiform layer (OPL) structures. (A) AAV-transduced area in treated animal. The GFP fluorescence in the photoreceptors is clearly discernible. (B) Untreated control. (C,D) Higher magnification images of the areas highlighted in panels (A,B) with antibodies against C-terminal-binding protein 2 (CtBP2) (red) staining photoreceptor synaptic ribbons and calcium-binding protein (CaBP) (green) marking horizontal cells. (E,F) OPL of treated (left) and untreated (right) retinas with antibodies for DHP (red) marking voltage-gated calcium channels on invaginating bipolar cell dendritic tips and PKCα (green) marking rod bipolar cells. (G,H) OPL of treated (left) and control (right) retinas with antibodies for PSD95 (red) and CaBP (green). Structure and arrangement as well as overall number of synaptic contacts between first and second order neurons do not appear to be altered in treated retinas. n = 5 AAV-transduced eyes and n = 5 untreated controls. Abbreviations: compare Figure 1. Scale bar in panel (B) [for panels (A,B)]: 20 µm; scale bar in panel (F) [for panels (C–H)]: 10 µm.