Figure 5. Monkey K. Plastic section (1 μm) of the right eye, stained with Toluidine blue, passing between the arrows shown in Figure 2. The precise location was pinpointed by the junction between the vein and its branch, which can be seen in the retinal photograph, although it is a bit out of focus. Near the optic disc, large vessels are situated in the nerve fiber layer, which becomes especially thickened. The vein branch enters and disrupts the ganglion cell layer. The artery on the left, the angioscotoma representation of which is marked by an arrowhead in Figure 2, has a lumen diameter of 57 μm. This was calculated by measuring the lumen circumference and dividing by π (we assumed the oval shape was a postmortem artifact). The small arrows denote four ellipsoids of cone inner segments, located underneath the artery. NFL, Nerve fiber layer; GCL, ganglion cell layer; IPL, inner plexiform layer; INL, inner nuclear layer; OPL, outer plexiform layer; ONL, outer nuclear layer; IS, inner segments; OS, outer segments; PE, pigment epithelium.