Transcutaneous access to retrograde axonal flow.

Transcutaneous entry of fluorescent tracer and subsequent retrograde neuronal transport achieved by the use of dimethyl sulfoxide (DMSO) as a vehicle fluorescent dye dissolved in DMSO and applied topically to the hind limb of rats was found in corresponding dorsal root ganglia; aqueous absorption of tracer dye by neuronal tissue was not demonstrated. This example of transcutaneous access and retrograde transport may have implications as to the entry of various toxins, viruses, chemicals, and therapeutic agents to the nervous system.