The hazzards of using optic nerve (as opposed to optic tract and more distal components of
the optic system) to study axonal transport were highlighted by observing the fate of [14 C]
serine and [3 H] glycerol injected into the rabbit eye. Despite prior blockage of axonal
transport with colchicine, appreciable radioactivity rapidly appeared in the optic nerve
adjacent to the injected eye. Radioactivity decreased exponentially along the entire optic
nerve in the somato-axonal direction, extending up to but not beyond the optic chiasm …