Anterograde and transcellular transport of a fluorescent dye, bisbenzimide, in the rat visual system

Fluorescent labeling was seen in rat brain after injections of 10 microliters of 10% bisbenzimide into the posterior chamber of the eye. Small and spindle shaped fluorescent nuclei were seen in the ipsilateral optic nerve, chiasm and contralateral optic tract, while larger apparently neuronal nuclei were seen in regions such as the lateral geniculate and superior colliculus where the retinal projection terminates. These experiments suggest that, like radioactive compounds, fluorescent dyes undergo anterograde and transcellular transport following large injections. Although limited by sensitivity and the large injection volumes required, this anterograde transport and transcellular transfer of bisbenzimide may be useful in identifying cell populations near the terminal projections of specific neuronal pathways.