(
A,
B) Porcine full-thickness retina fixed immediately after detachment from RPE. Retinas prepared in this manner served as controls. (
A) Retina immunolabeled with SV2 (
green), stained with propidium iodide (
red) and viewed in a 2-μm optical section with laser scanning confocal microscopy. OS (
arrows) and IS (
arrowheads) appear intact with the OS uniformly organized and properly oriented. (
B) An alternative staining, retina immunolabeled with synaptophysin (
green) and rod-specific opsin (4D2;
red) and viewed in a 1-μm optical section. SV2 and synaptophysin uniformly label both plexiform layers. Propidium iodide stained the nuclear layers, whereas 4D2 was confined to rod OS. (
B) Cone IS exhibited autofluorescence that was distinct from 4D2 labeling of rod OS. (
C) Morphometric analysis, illustrated in a photoreceptor sheet. To quantify the spread of synaptic labeling, the area of SV2 labeling within the ONL was measured within a set rectangular frame (
dashed lines). ONL thickness was quantified by measuring the distance from the base of the IS to the base of the innermost cell body of the ONL (
double-headed arrow). A count of the ONL cell layers was made along the same perpendicular line. (
D) A higher magnification of (
A) depicting the characteristic large, triangular-shaped cone pedicles (
arrows) and smaller globular rod spherules (
arrowheads). Note the bilaminar arrangement of the photoreceptor terminals with the spherules located sclerad to the cone terminals. On occasion, dark puncta were present in photoreceptor terminals. They represent synaptic invaginations (
arrow 
and
arrowhead 
). OS, outer segments; IS, inner segments; ONL, outer nuclear layer; OPL, outer plexiform layer, INL, inner nuclear layer, IPL, inner plexiform layer; GCL, ganglion cell layer; and NFL, nerve fiber layer. Scale bar: (
A) 50 μm; (
B) 25 μm; (
D) 10 μm.