Structure of the nerve endings on the external hair cells of the guinea pig cochlea as studied by serial sections

Smith, Catherine A.; Sjöstrand, Fritiof S.

doi:10.1016/s0022-5320(61)80025-7

Cited by 257 publications

(74 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2) and from base to apex ( Fig. 1 H and I), correspond in distribution to the large efferent endings on outer hair cells as described (20,22,23). This indicates that the olivocochlear system predominantly innervating outer hair cells contains enkephalin-like immunoreactivity.…”

supporting

confidence: 60%

“…Large synaptic terminals on outer hair cells are endings ofupper tunnel crossing fibers (9,12,16) and are efferent (18,19). Smaller efferent endings form synapses with auditory nerve dendrites at the outer hair cell bases (20,21). The efferent innervation is maximal in the first and second turns ofthe cochlea and diminishes towards the apex (22,23).…”

mentioning

confidence: 99%

“…This indicates that the olivocochlear system predominantly innervating outer hair cells contains enkephalin-like immunoreactivity. The small and relatively few auditory nerve synapseswith outer hair cells (9,12,20) would be unlikely to give rise to the relatively large fluorescent patches that were found in outer hair cell synaptic regions in both the guinea pig and cat (Fig. 2), particularly in basal turns.…”

mentioning

confidence: 99%

“…Previous studies reported evidence for (17) and against (9) the presence ofefferent fibers at this level of the tunnel. Two types of outer hair cells have been described (20), corresponding to the distribution of efferent endings. Type B cells, with mostly small efferent endings, were seen in the outer row ofhair cells in the second turn and in the outer two rows in the third and fourth turns (20).…”

mentioning

confidence: 99%

“…Two types of outer hair cells have been described (20), corresponding to the distribution of efferent endings. Type B cells, with mostly small efferent endings, were seen in the outer row ofhair cells in the second turn and in the outer two rows in the third and fourth turns (20). Conceivably, the immunofluorescent low tunnel crossing fibers, also seen predominantly in the third and fourth turns, represented efferents leading to type B outer hair cells.…”

mentioning

confidence: 99%

See 4 more Smart Citations

Enkephalin-like immunoreactivity of olivocochlear nerve fibers in cochlea of guinea pig and cat

Fex

Altschuler

1981

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

The distribution ofenkephalin-like immunoreactivity in the cochlea ofthe guinea pig and cat was studied. Indirect immunofluorescence immunohistochemistry using antisera generated against a methionine enkephalin-bovine thyroglobulin conjugate was applied to surface preparations of the organ of Corti and cryostat sections of the whole of the cochlea. In the cochlear osseous spiral lamina, immunofluorescence was localized to unmyelinated fibers ofthe intraganglionic spiral bundle. In the organ of Corti, immunofluorescence was localized to a small number of fibers at inner hair cells, the inner spiral bundle, and tunnel spiral bundle, to tunnel crossing fibers at the level of the tunnel floor, to an occasional spiral outer fiber, and to the synaptic region ofouter hair cells in the three rows of the basal turn of the cochlea. Less immunofluorescence was found in this region as one progressed towards the apex, with none seen at the apex. At the most apical region the inner spiral bundle became patchy and the tunnel spiral bundle developed arcades. There was no immunofluorescence found in spiral ganglion cells, in auditory nerve fibers, or in the hair cells of the organ of Corti. The findings were the same in cat as in guinea pig, the latter being studied in more detail. It was concluded that efferent, olivocochlear neurons ofthe cochlea, synapsing predominantly with primary auditory nerve fibers from the inner sensory cells or with the sensory cells, contain enkephalin-like immunoreactivity. Also, the findings indicate that endings of olivocochlear neurons that synapse predominantly with outer hair cells contain enkephalin-like immunoreactivity. It has previously been shown that ofivocochlear neurons are likely to be cholinergic.Methionine enkephalin and leucine enkephalin are opioid pentapeptides originally isolated from the whole brain (1, 2). Immunohistochemical mapping of enkephalin-like immunoreactivity in the central nervous system was done (3-5), and it was noted that in certain regions enkephalin-like immunoreactivity and opiate receptors had a similar distribution (3, 5). A much entertained working hypothesis is that enkephalins may act as neurotransmitters or modulate the action of neurotransmitters (6).In the organ ofCorti, each inner hair cell synapses with about 20 auditory nerve boutons from about 90% of the total spiral ganglion cell population (7-9). The outer hair cells make relatively few synapses with auditory nerve boutons from about 10% of the spiral ganglion cells (7-9). The auditory receptor organ also receives efferent, centrifugal innervation from the brainstem, through olivocochlear neurons. In the cochlea, myelinated and unmyelinated olivocochlear fibers spiral in the fascicles ofthe intraganglionic bundle (10, 11) and then fan out to the organ of Corti. In the organ of Corti, such fibers form the inner spiral bundle and the tunnel spiral bundle (12)(13)(14). Inner hair cells and auditory nerve dendrites under inner hair cells receive efferent innervation from the inner spiral bundl...

show abstract

supporting

confidence: 60%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Enkephalin-like immunoreactivity of olivocochlear nerve fibers in cochlea of guinea pig and cat

Fex

Altschuler

1981

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

Compound synapses within the GABAergic innervation of the auditory inner hair cells in the adolescent mouse

et al. 1997

View full text Add to dashboard Cite

Ultrastructural investigation of the gamma-aminobutyric acid (GABA) component of the inner spiral bundle in adolescent mice revealed a pathway of glutamic acid decarboxylase (GAD)-positive and -negative fibers and vesiculated endings that contact inner hair cells and their afferents through a complex of axosomatic and axodendritic synapses. Ultrastructural details were investigated by using conventional electron microscopy. Several synaptic arrangements were observed: Main axosomatic synapses form between vesiculated endings and individual or adjoining inner hair cells (interreceptor synapses). Spinous synapses form on long, spinelike processes that protrude from inner hair cells to reach distant efferent endings. The efferent endings associate with inner hair cells and their synaptic afferents through compound synapses-serial, "converging," and triadic-otherwise characteristic of sensory relay nuclei. Serial synapses form by the sequential presynaptic alignment of the efferent-->receptor-->afferent components. Converging synapses result from the simultaneous apposition of a receptor ribbon synapse and a presynaptic efferent terminal on a recipient afferent dendrite. Triadic synapses comprise a vesiculated efferent ending in contact with an inner hair cell and with its synaptic afferent. Additionally, efferent endings may form simple axodendritic and axoaxonal synapses with GAD-negative vesiculated endings. The combination of different synaptic arrangements leads to short chains of compound synapses. It is assumed that these synaptic patterns seen in the adolescent mouse represent adult synaptology. The patterns of synaptic connectivity suggest an integrative role for the GABA/GAD lateral efferent system, and imply its involvement in the pre- and postsynaptic modulation of auditory signals.

show abstract

Plasticity of retinal ribbon synapses

Vollrath

Spiwoks-Becker

1996

Microsc. Res. Tech.

View full text Add to dashboard Cite

Ribbon synapses differ from conventional chemical synapses in that they contain, within the cloud of synaptic vesicles (SV's), a specialized synaptic body, most often termed synaptic ribbon (SR). This body assumes various forms. Reconstructions reveal that what appear as rod‐ or ribbon‐like profiles in sections are in fact rectangular or horseshoe‐shaped plates. Moreover, spherical, T‐shaped, table‐shaped, and highly pleomorphic bodies may be present. In mammals, ribbon synapses are present in afferent synapses of photoreceptors, bipolar nerve cells, and hair cells of both the organ of Corti and the vestibular organ. Synaptic ribbons (SR's) are also found in the intrinsic cells of the third eye, the pineal gland, and in the lateral line system. The precise function of SR's is enigmatic. The prevailing concept is that SR's function as conveyor belts to channel SV's to the presynaptic membrane for neurotransmitter release by means of exocytosis. The present article reviews the evidence that speaks for a plasticity of these organelles in the retina and the third eye, as reflected in changes in number, size, shape, location, and grouping pattern. SR plasticity is especially pronounced in the mammalian and submammalian pineal gland and in cones and bipolar cells of teleost fishes. Here, SR number and size wax and wane according to the environmental lighting conditions. In the pineal SR numbers increase at night and decrease during the day. In teleost cones, SR's are in their prime during daytime and decrease or disappear at night, when transmitter release is enhanced. In addition to numerical changes, SR's may also exhibit changes in size, shape, grouping pattern, and location. In the mammalian retina of adults, in contrast to the developing retina, the reported signs of SR plasticity are subtle and not always consistent. They may reflect changes in function or may represent signs of degradation. To distinguish between the two, more detailed studies under selected experimental conditions are required. Probably the strongest evidence for SR plasticity in the mammalian retina is that in hibernating squirrels SR's leave the synaptic site and accumulate in areas as far as 5 μm from the synapse. Changes in shape include the occurrence of club‐shaped SR's and round SR's or synaptic spheres (SS's). SS's may represent a special type of synaptic body, yet belonging to the family of SR's, or may be related to the catabolism of SR's. SR number is regulated by Ca2+ in teleost cones, whereas in the mammalian pineal gland cGMP is involved. An interesting biochemical feature of ribbon synapses is that they lack synapsins. The presently reviewed results suggest to us that SR's do not primarily function as conveyor belts, but are devices to immobilize SV's in inactive ribbon synapses. © 1996 Wiley‐Liss, Inc.

show abstract

Structure of the nerve endings on the external hair cells of the guinea pig cochlea as studied by serial sections

Cited by 257 publications

References 26 publications

Enkephalin-like immunoreactivity of olivocochlear nerve fibers in cochlea of guinea pig and cat

Enkephalin-like immunoreactivity of olivocochlear nerve fibers in cochlea of guinea pig and cat

Compound synapses within the GABAergic innervation of the auditory inner hair cells in the adolescent mouse

Plasticity of retinal ribbon synapses

Contact Info

Product

Resources

About