Figure 2. Confocal immunofluorescent images of normal and detached cat retina. A: This projection of a z-series consisting of 3 0.5 µm-thick optical sections of normal cat retina triple-labeled with anti-protein kinase C (PKC), anti-VAMP2, and anti-neurofilament shows the tightly-clustered synaptic terminals of rods (r) and cones (c; green). Anti-PKC (red) labels the rod bipolar (RB) cells whose apical processes cross the outer plexiform layer (OPL) neuropil to reach the rod spherules but never normally extend into the outer nuclear layer (ONL). Anti-neurofilament (blue) labels an A-type HC (HA) lying in the inner nuclear layer (INL). Scale bar represents 12 μm. B: This projection of a z-series consists of 5 0.5 µm-thick optical sections of retina that was detached for 28 days, sectioned, and then triple-labeled with anti-PKC, anti-VAMP2, and anti-neurofilament. Labeled RB outgrowths (red) extend into the ONL where they terminate (arrows) adjacent to VAMP2-positive retracted rod terminals (green). The RB nuclei lie slightly deeper in the outer INL than an HA labeled with anti-neurofilament (blue). Scale bar as in A. C: This projection of a z-series consists of 3 0.5 µm-thick optical sections of normal cat retina that was double-labeled with anti-calretinin and anti-VAMP2. Rod spherules (r) labeled with anti-VAMP2 (green) are closely clumped together at the inner margin of the ONL. The cell body of a B-type HC (HB) is labeled with anti-calretinin (red). A small branch of a HC axon terminal rises to innervate several spherules (arrow) but does not extend into the ONL itself. Scale bar as in A. D: This projection of a z-series of 5 1.0 µm-thick optical sections of 7-day detached cat retina shows a loose assembly of anti-VAMP2-labeled rod spherules (green) in the OPL as well as retracting spherules at various depths of the ONL. Outgrowths from B-type HCs labeled with anti-calretinin (red) extend into the ONL to terminate near retracted rod spherules (arrows). The soma of a B-type HC is labeled (HB). Scale bar indicates 10 μm.