Retrograde axonal transport of horseradish peroxidase by ganglion cells of the albino rat retina

Abstract

After introduction of small amounts of horseradish peroxidase (HRP) into known visual centers of the brain, retinal ganglion cells projecting to these regions were detected by the accumulation of HRP-positive granules in their somata. Control experiments indicated that the HRP-positive granules had reached the ganglion cell somata by retrograde axonal transport, and did not represent blood-borne or endogenous peroxidase. Using this technique, it has been determined that axons of both large and medium-sized neurons in the ganglion cell layer of adult and immature rat retinae terminate in the superior colliculus and lateral geniculate body, and that characteristic displaced ganglion cells with axonal connections to these visual centers occur regularly in these retinae. In addition, certain small cells in the retinal ganglion cell layer are described which may represent glia or interneurons, or ganglion cells which lack the ability to transport peroxidase or which lack central connections to these visual centers of the brain.