[Evaluation of dermatomes in the hind paw of the rat using retrograde axonal transport].

UV light fluorescent tracers (True Blue and Fast Blue) are placed in contact with sensitive receptors after dermabrasion. The abraded surfaces are limited to two hemidorsal areas and two hemi plantar areas on the animals' foot. A five days survival is allowed to enable the axonal retrograde transport of the tracers, then the animals are sacrificed and perfused with an intracardiac injection of 10% formaldehyde in phosphate buffer at 7.4 pH. The lumbar spinal ganglions are immediately dissected out, examined as a whole with a Leitz Dialux fluorescence microscope, then frozen and cut with a cryotome. The results of this analysis show that: i-only ipsilateral dorsal root ganglions are labeled by blue dye. ii-the number of fluorescent cells varies between 20 to 60 per ganglion. iii-a map of the distribution of the dermatomes on the rat hind foot can be deducted from the study of the labelled ganglions. They spread from L2 to L5 from the cranial to the caudal part, and from the medial to the lateral side of the rat foot, on both dorsal and plantar areas.