DISTRIBUTION OF THE DICHOTOMIZING BRANCHES OF PERIPHERAL PROCESSES OF CAUDAL LUMBAR DORSAL ROOT GANGLION NEURONS IN THE RAT——A DOUBLE FLUORESCENCE LABELLING STUDY / 解剖学报

ABSTRACT

The technique of double labelling with fluorescent tracers(FB-NY,PI-Bb)has.been used in the following three groups of experiments1.in 5 rats,one fluorescenttracer was injected into the tibial nerve and the other was injected into the peronealnerve;2.in 14 rats,one fluorescent tracer was injected into the sural cutaneousnerve and the other was injected into the branches to the soleus and gastrocnemiusmuscles;3.in 13 rats,one tracer was injected into the tibial nerve and the otherinto the bladder wall.The sections of the L_(3-6),S_(1-3) dorsal root ganglion were stu-died with a olympus fluorescence microscope using UG-1 excitation filter system.In the first and second groups,double labelled neurons were observed in L_(4-6) dorsalroot ganglion.But in the third group,the double labelled neurons were found onlyin the L_6 segment.The type of the double labelled neurons was mainly small-sized(33.1%)and small-medium sized(40.9%).The findings indicated that,the primary afferent fibers branched towards theperiphery and supplied,with different branches,either two somatic areas or skinand deep structures,or,especially,visceral and somatic sensory fields.This resultsuggests that the peripheral dichotomization of these dorsal root ganglion cells mightconverge sensory inputs from the somatic(tibial nerve)and the visceral(bladderwall)fields and thus provides one of the structural basis for the referred pain andthe neuronal mechanism of acupunctural therapy by which stimulation of somaticstructures could regulate the activities of visceral organs.