Effects of antibodies to large retinal ganglion cells on developing retinogeniculate pathways in the cat.

We investigated the effects of polyclonal antibodies, produced against ox large retinal ganglion cells, on the developing retinogeniculate pathways of cats. Four-week-old kittens were given an intraocular injection of either a low or a high concentration of the antibodies and effects were assessed 35-69 weeks later. After a low concentration (110 micrograms/33 microliter volume) injection, the density of retinal alpha-cells (the morphological counterpart of Y-cells) was reduced 44% in area centralis and 37% in peripheral retina. After a high concentration (333 micrograms/33 microliter volume) injection, alpha-cell density was reduced 76% in area centralis and 91% in peripheral retina. The same concentration of antibodies had no consistent effect on the numbers of medium- or small-size retinal ganglion cells. Electrophysiological recordings from single neurons in layers A and A1 of the lateral geniculate nucleus (LGN) revealed a 53% decrease in the percentage of Y-cells after a low-concentration injection and an 82% decrease after a high-concentration injection. There was a concomitant increase in the percentage of LGN cells that were non-responsive to light or that responded too poorly to be classified. No change was observed in the percentages of LGN X-cells or cells with mixed response properties. The reduced encounter rate of LGN Y-cells was not accompanied by significant changes in LGN cell-body size. Together, the results indicate that the immunoablation technique produces a large and apparently selective reduction of the Y-cell retinogeniculate pathway in developing kittens.