The terminal of the sympathetic nerve fibers in the facial nerve.
OBJECTIVE
The terminal of the sympathetic nerve fibers of the rat facial nerve in the temporal bone region was investigated.


METHODS
We used tyrosine hydroxylase (TH) and the synaptophysin antibody as markers of the sympathetic nerve fiber and the membrane of the synaptic vesicle, respectively. Using immunohistochemistry, we determined whether and where the synapse exists in the facial nerve of the Sprague-Dawley rat.


RESULTS
TH-immunoreactive fibers were confirmed as being present in both the epineurium and the nerve fascicle of the facial nerve. A synaptophysin immunoreaction was found in the facial nerve in a region of the temporal bone. These reaction products looked like varicosities. Most TH-positive fibers in the facial nerve disappeared after superior cervical ganglionectomy.


CONCLUSIONS
As the synaptophysin immunoreaction indicates the existence of a synapse, we speculate that the sympathetic fibers affect the facial nerve in the region of the temporal bone. Further studies may be needed to elucidate the function of the sympathetic system in the facial nerve.
Department of Otorhinolaryngology, Matsunami General Hospital, Gifu, Japan. syoshi@matsunami-hsp.or.jp
Yoshiyuki
Y
Shibamori
Takehisa
T
Saito
Masaharu
M
Tokuriki
Shigeharu
S
Fujieda
Hitoshi
H
Saito
D000818:Animals; D015415:Biomarkers / Q000032:analysis; D005154:Facial Nerve / Q000033:anatomy & histology* / Q000648:ultrastructure; D007150:Immunohistochemistry; D016253:Microscopy, Immunoelectron; D051381:Rats; D017207:Rats, Sprague-Dawley; D017779:Sympathetic Fibers, Postganglionic / Q000033:anatomy & histology* / Q000648:ultrastructure; D013569:Synapses; D016708:Synaptophysin / Q000032:analysis / Q000276:immunology; D013701:Temporal Bone / Q000294:innervation
D015415:Biomarkers; D016708:Synaptophysin