A retrograde double-labelling study of retinal ganglion cells that project ipsilaterally to vLGN and LPN rather than dLGN and SC, in albino rat

We studied ipsilaterally projecting, double-labeled retinal ganglion cells that have bifurcating axons by retrograde fluorescent double-labeling in albino rats. Ten albino (Wistar, Japan Clea) rats of either sex, weighing 350–400 g were used. With the rats in a state of deep anesthesia, we pressure-injected 0.02 μl of 15% Evans blue (EB) into the right ventral lateral geniculate nucleus (vLGN), and 4% Fluoro-gold (FG) iontophoretically into the right posterior lateral thalamic nucleus (LP). The animals were perfused with formol-saline 48–72 h later and both the brain and eyes were excised. The brain was sectioned coronally, and each retina was removed and mounted flat on a glass slide. Double-labeled cells were found in the ventral temporal crescent of the retina. In one animal the total number of ipsilaterally labeled cells was 566, and the percentages of double-labeled vLGN and LP projecting cells, single-labeled vLGN projecting cells, and single-labeled LP projecting cells were 29.8, 58.8 and 11.3, respectively.