Dorsal root ganglion neurons with central processes in both dorsal and ventral roots in rats.

Axonal transport of fluorescent dyes, Diamidino yellow dihydrochloride (DY) and Fast blue (FB), applied to the cut distal ends of dorsal and ventral roots, respectively, was studied in order to determine whether any dorsal root ganglion (DRG) neurons have processes in both dorsal and ventral roots. A total of 359 DRG neurons are double labeled in 14 ganglia (L6 and S1) from 6 different animals, thus suggesting a possibility of many DRG neurons having multiple central processes. The somata of the double-labeled DRG neurons are small to medium in size with a mean diameter of 29 microns. These data are consistent with findings that the majority of ventral root afferent fibers are unmyelinated or small myelinated axons.