The terminal of the sympathetic nerve fibers in the facial nerve

Objective The terminal of the sympathetic nerve fibersof the rat facial nervein the temporal boneregion was investigated. Material and Methods We used tyrosine hydroxylase(TH) and the synaptophysinantibody as markers of the sympathetic nerve fiberand the membrane of the synaptic vesicle, respectively. Using immunohistochemistry, we determined whether and where the synapse exists in the facial nerveof the Sprague–Dawley rat. Results TH-immunoreactive fibers were confirmed as being present in both the epineuriumand the nerve fascicleof the facial nerve. A synaptophysinimmunoreaction was found in the facial nervein a region of the temporal bone. These reaction products looked like varicosities. Most TH-positive fibers in the facial nervedisappeared after superior cervical ganglionectomy. Conclusions As the synaptophysinimmunoreaction indicates the existence of a synapse, we speculate that the sympathetic fibers affect the facial nervein the region of the temporal bone. Further studies may be ne...