Figure 3.

AAV2/1-synapsin-1-mediated expression patterns in the mouse retina. Laser-scanning confocal microscope images of GCaMP3 expression (green) 2 weeks after intravitreal injection of AAV2/1-syn1-GCaMP3 into adult mouse eyes. Tissues were counterstained with the nuclear stain DAPI (blue). A, An injection volume of 0.75 μl typically gave a spotted transfection pattern, with several clusters of ∼20–100 brightly labeled cells (white box magnified in B) distributed across the retina. The superficial fiber layer showed bundles of fluorescent axons converging on the optic disc (open arrowhead). Almost all transfected retinas showed labeled cells concentrated at the perimeter of the optic disc (solid arrowhead). B, Higher magnification of the boxed area in A. C, A greater injection volume (1.0–2.0 μl) often gave more uniform labeling, faster expression, and generally higher expression levels (not quantified). Scale bars: A, C, 1.0 mm; B, 25 μm.