Sensory innervation of the ear drum and middle-ear mucosa: retrograde tracing and immunocytochemistry.
The distribution and origin of nerve fibers of presumed sensory nature in the ear drum and middle-ear mucosa of the rat were studied by a retrograde tracing technique in combination with immunocytochemistry. Application of True Blue (TB) on the ear drum or on the middle-ear mucosa labeled nerve cell bodies in the jugular, trigeminal, geniculate and cervical dorsal root ganglia (C2-C4). Judging from the number of TB-labeled nerve cell bodies the jugular and trigeminal ganglia contributed the major component to the sensory innervation of the ear drum and the middle-ear mucosa, while the contribution from the geniculate and cervical dorsal root ganglia was relatively minor. The majority of the TB-labeled nerve cell bodies contained calcitonin gene-related peptide (CGRP), whereas minor populations stored substance P (SP) and neurokinin A (NKA). Nerve fibers containing SP, NKA and CGRP were moderate in number in the middle-ear mucosa and few in the ear drum. Double immunostaining revealed that SP invariably coexisted with NKA in nerve cell bodies in the ganglia examined. The SP/NKA-containing nerve cell bodies constituted a subpopulation of those storing CGRP. The findings indicate that several ganglia project to the ear drum and middle-ear mucosa and that many neuropeptides are involved in the mediation of middle-ear sensitivity.
Uddman
R
R
Department of Otorhinolaryngology, Malmö General Hospital, Sweden.
Grunditz
T
T
Larsson
A
A
Sundler
F
F
D000344:Afferent Pathways / Q000166:cytology / Q000502:physiology; D000818:Animals; D001370:Axonal Transport; D001572:Benzofurans; D004432:Ear, Middle / Q000166:cytology / Q000294:innervation*; D005260:Female; D005455:Fluorescent Antibody Technique; D005456:Fluorescent Dyes; D009092:Mucous Membrane / Q000166:cytology / Q000294:innervation; D009475:Neurons, Afferent / Q000166:cytology / Q000502:physiology*; D009479:Neuropeptides / Q000032:analysis; D051381:Rats; D011919:Rats, Inbred Strains; D014276:Trigeminal Nerve / Q000166:cytology / Q000502:physiology
D001572:Benzofurans; D005456:Fluorescent Dyes; D009479:Neuropeptides; C038675:true blue