WordNet

reveal (something) about somebodys identity or lifestyle; "The gay actor was outed last week"; "Someone outed a CIA agent"
(baseball) a failure by a batter or runner to reach a base safely in baseball; "you only get 3 outs per inning"
be made known; be disclosed or revealed; "The truth will out" (同)come_out
away from home; "they went out last night"
directed outward or serving to direct something outward; "the out doorway"; "the out basket"
moving or appearing to move away from a place, especially one that is enclosed or hidden; "the cat came out from under the bed";
no longer fashionable; "that style is out these days"
not allowed to continue to bat or run; "he was tagged out at second on a close play"; "he fanned out"
not worth considering as a possibility; "a picnic is out because of the weather"
out of power; especially having been unsuccessful in an election; "now the Democrats are out"
outer or outlying; "the out islands"
outside or external; "the out surface of a ships hull"
small room in which a monk or nun lives (同)cubicle
a device that delivers an electric current as the result of a chemical reaction (同)electric cell
a room where a prisoner is kept (同)jail cell, prison cell
(biology) the basic structural and functional unit of all organisms; they may exist as independent units of life (as in monads) or may form colonies or tissues as in higher plants and animals
any small compartment; "the cells of a honeycomb"
a small unit serving as part of or as the nucleus of a larger political movement (同)cadre
filamentous hairlike growth on a plant; "peach fuzz" (同)fuzz, tomentum
a filamentous projection or process on an organism
any of the cylindrical filaments characteristically growing from the epidermis of a mammal; "there is a hair in my soup" (同)pilus
a covering for the body (or parts of it) consisting of a dense growth of threadlike structures (as on the human head); helps to prevent heat loss; "he combed his hair"; "each hair consists of layers of dead keratinized cells"
located outside; "outer reality"
being on or toward the outside of the body; "the outer ear"
being on the outside or further from a center; "spent hours adorning the outer man"; "the outer suburbs"

PrepTutorEJDIC

(ある位置・状態から)『外へ』(『で』),外出して;戸外に;外国に / (隠れた所から表面に)『現れ出て』;世に出て;発表されて;(花・葉などが)出て来て,咲いて / 『無くなって』,消えて;終わって;流行遅れの,すたれた / 『最後まで』,すっかり / 大声で,はっきりと,隠さずに / (政権・現職から)離れて,去って / 仕事を休んで;ストライキをやって / (調子が)狂って,乱れて,(関節などが)はずれて;まちがって;損をして / (野球・クリケットで)アウトになって(ボクシングで)ノックアウトになって / 支配権を失った,政権から離れた / (野球・クリケットで打者・走者が)アウトになった / (衣服などが)並はずれて大きい,特大の / 遠く離れた / 《米》…から[外に(を)] / 《米》…に沿って外へ,のはずれに / (野球・クリケットで)アウト;《the outs》守備測 / 《複数形で》失業者 / 《米話》言い訳,口実 / ばれる,露見する / 出て行け
(刑務所の)『独房』;(修道院の)小さい独居室 / (ミツバチの)みつ房,巣穴 / 小さい部屋 / 『細胞』 / 電池 / 花粉室 / (共産党などの)細胞
〈C〉(人間・動物の1本の)『毛』;(植物・昆虫などの)毛 / 〈U〉《集合的に》『髪の毛』,毛,毛髪;(動物の)体毛 / 《a~》1本の毛ほどの量(距離,程度),ごくわずか
外に,外側の,外部の / 中心から遠い
おや,はああ,ああ(驚き・喜び・疑い・ためらいなどを表す声)
hectare; hectares

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/06/13 12:34:59」(JST)

wiki en

Hair cells are the sensory receptors of both the auditory system and the vestibular system in all vertebrates. In mammals, the auditory hair cells are located within the organ of Corti on a thin basilar membrane in the cochlea of the inner ear. They derive their name from the tufts of stereocilia that protrude from the apical surface of the cell, a structure known as the hair bundle, into the scala media, a fluid-filled tube within the cochlea. Mammalian cochlear hair cells come in two anatomically and functionally distinct types: the outer and inner hair cells. Damage to these hair cells results in decreased hearing sensitivity, i.e. sensorineural hearing loss.

Hair bundles as sound detectors and amplifiers

Research of the past decades^[who?] has shown that outer hair cells do not send neural signals to the brain, but that they mechanically amplify low-level sound that enters the cochlea. The amplification may be powered by movement of their hair bundles, or by an electrically driven motility of their cell bodies. The inner hair cells transform the sound vibrations in the fluids of the cochlea into electrical signals that are then relayed via the auditory nerve to the auditory brainstem and to the auditory cortex.

Results in recent years^{[by whom?]} further indicate that mammals apparently have conserved an evolutionarily earlier type of hair-cell motility. This so-called hair-bundle motility amplifies sound in all non-mammalian land vertebrates. It is affected by the closing mechanism of the mechanical sensory ion channels at the tips of the hair bundles. Thus, the same hair-bundle mechanism that detects sound vibrations also actively "vibrates back" and thereby mechanically amplifies weak incoming sound.

Inner hair cells – from sound to nerve signal

Section through the organ of corti, showing inner and outer hair cells

The deflection of the hair-cell stereocilia opens mechanically gated ion channels that allow any small, positively charged ions (primarily potassium and calcium) to enter the cell.^[1] Unlike many other electrically active cells, the hair cell itself does not fire an action potential. Instead, the influx of positive ions from the endolymph in Scala media depolarizes the cell, resulting in a receptor potential. This receptor potential opens voltage gated calcium channels; calcium ions then enter the cell and trigger the release of neurotransmitters at the basal end of the cell. The neurotransmitters diffuse across the narrow space between the hair cell and a nerve terminal, where they then bind to receptors and thus trigger action potentials in the nerve. In this way, the mechanical sound signal is converted into an electrical nerve signal. The repolarization in the hair cell is done in a special manner. The Perilymph in Scala tympani has a very low concentration of positive ions. The electrochemical gradient makes the positive ions flow through channels to the Perilymph.

Hair cells chronically leak Ca²⁺. This leakage causes a tonic release of neurotransmitter to the synapses. It is thought that this tonic release is what allows the hair cells to respond so quickly in response to mechanical stimuli. The quickness of the hair cell response may also be due to that fact that it can increase the amount of neurotransmitter release in response to a change as little as 100 μV in membrane potential.^[2]

Outer hair cells – acoustical pre-amplifiers

In mammalian outer hair cells, the receptor potential triggers active vibrations of the cell body. This mechanical response to electrical signals is termed somatic electromotility^[3] and drives oscillations in the cell’s length, which occur at the frequency of the incoming sound and provide mechanical feedback amplification. A movie clip showing an isolated outer hair cell moving in response to electrical stimulation can be seen here. Outer hair cells are found only in mammals. While hearing sensitivity of mammals is similar to that of other classes of vertebrates, without functioning outer hair cells, the sensitivity decreases by approximately 50 dB^[who?]. Outer hair cells extend the hearing range to about 200 kHz in some marine mammals.^[4] They have also improved frequency selectivity (frequency discrimination), which is of particular benefit for humans, because it enabled sophisticated speech and music.

The effect of this system is to non-linearly amplify quiet sounds more than large ones, so that a wide range of sound pressures can be reduced to a much smaller range of hair displacements.^[5] This property of amplification is called the cochlear amplifier.

The molecular biology of hair cells has seen considerable progress in recent years, with the identification of the motor protein (prestin) that underlies somatic electromotility in the outer hair cells. Santos-Sacchi et al. have shown that prestin's function is dependent on chloride channel signalling and that it is compromised by the common marine pesticide tributyltin (TBT). Because this class of pollutant bioconcentrates up the food chain, the effect is pronounced in top marine predators such as orcas and toothed whales.^[6]

Neural connection

Neurons of the auditory or vestibulocochlear nerve (the VIIIth cranial nerve) innervate cochlear and vestibular hair cells.^[7] The neurotransmitter released by hair cells that stimulates the terminal neurites of peripheral axons of the afferent neurons is thought to be glutamate. At the presynaptic juncture, there is a distinct presynaptic dense body or ribbon. This dense body is surrounded by synaptic vesicles and is thought to aid in the fast release of neurotransmitter.

Nerve fiber innervation is much denser for inner hair cells than for outer hair cells. A single inner hair cell is innervated by numerous nerve fibers, whereas a single nerve fiber innervates many outer hair cells. Inner hair cell nerve fibers are also very heavily myelinated, which is in contrast to the unmyelinated outer hair cell nerve fibers. The region of the basilar membrane supplying the inputs to a particular afferent nerve fibre can be considered to be its receptive field.

Efferent projections from the brain to the cochlea also play a role in the perception of sound. Efferent synapses occur on outer hair cells and on afferent (towards the brain) axons under inner hair cells. The presynaptic terminal bouton is filled with vesicles containing acetylcholine and a neuropeptide called Calcitonin gene-related peptide (CGRP). The effects of these compounds varies, in some hair cells the acetylcholine hyperpolarized the cell, which reduces the sensitivity of the cochlea locally.

Regrowth

Research on the regrowth of cochlea cells may lead to medical treatments that restore hearing. Unlike fish, birds, and reptiles, post-birth humans and other mammals are normally unable to regrow the cells of the inner ear that convert sound into neural signals when those cells are damaged by loud sounds, age or disease.^[8] There is some contradictory information regarding the possibility of hair cell regeneration in mature mammals.^[9]^[10]^[11]

Researchers are making progress toward gene and stem-cell therapies that may allow the damaged cells to be regenerated.^[12] Researchers have identified a mammalian gene that normally acts as a molecular switch to block the regrowth of cochlear hair cells in adults.^[13] The Rb1 gene encodes the retinoblastoma protein that performs several physiological functions.^[14] Not only do hair cells in a culture dish regenerate when the Rb1 gene is deleted, but mice bred to be missing the gene grow more hair cells than control mice that have the gene. The cell cycle inhibitor p27kip1 has also been shown to allow regrowth of cochlear hair cells in mice following genetic deletion or knock down with siRNA targeting p27.^[15]^[16]^[17]

Additional images

The lamina reticularis and subjacent structures.
Inner ear illustration showing semicircular canal, hair cells, ampulla, cupula, vestibular nerve, & fluid
Stereocilia of frog inner ear

Notes

^ Müller, U (October 2008). "Cadherins and mechanotransduction by hair cells". Current opinion in cell biology 20 (5): 557–566. doi:10.1016/j.ceb.2008.06.004. PMC 2692626. PMID 18619539.
^ Chan DK, Hudspeth AJ (February 2005). "Ca2+ current-driven nonlinear amplification by the mammalian cochlea in vitro". Nature Neuroscience 8 (2): 149–155. doi:10.1038/nn1385. PMC 2151387. PMID 15643426.
^ Brownell WE, Bader CR, Bertrand D, de Ribaupierre Y (1985-01-11). "Evoked mechanical responses of isolated cochlear outer hair cells". Science 227 (4683): 194–196. Bibcode:1985Sci...227..194B. doi:10.1126/science.3966153. PMID 3966153.
^ Wartzog D, Ketten DR (1999). "Marine Mammal Sensory Systems". In J. Reynolds, S. Rommel. Biology of Marine Mammals. Smithsonian Institution Press. p. 132.
^ Hudspeth AJ (2008-08-28). "Making an effort to listen: mechanical amplification in the ear". Neuron 59 (4): 530–45. doi:10.1016/j.neuron.2008.07.012. PMC 2724262. PMID 18760690.
^ Santos-Sacchi Joseph, Song Lei, Zheng Jiefu, Nuttall Alfred L (2006-04-12). "Control of mammalian cochlear amplification by chloride anions". Journal of Neuroscience 26 (15): 3992–8. doi:10.1523/JNEUROSCI.4548-05.2006. PMID 16611815.
^ "Cranial Nerve VIII. Vestibulocochlear Nerve". Meddean. Retrieved 2008-06-04.
^ Edge AS, Chen ZY (2008). "Hair cell regeneration". Current Opinion in Neurobiology 18 (4): 377–82. doi:10.1016/j.conb.2008.10.001. PMID 18929656.
^ last1=Forge, A; Li, L; Corwin, JT; Nevill, G (1993). "Ultrastructural evidence for hair cell regeneration in the mammalian inner ear". Science 259 (5101): 1616–9. Bibcode:1993Sci...259.1616F. doi:10.1126/science.8456284. PMID 8456284.
^ Lefebvre first1=PP; Malgrange, B; Staecker, H; Moonen, G; Van De Water, TR (1993). "Retinoic acid stimulates regeneration of mammalian auditory hair cells". Science 260 (5108): 692–5. Bibcode:1993Sci...260..692L. doi:10.1126/science.8480180. PMID 8480180.
^ Edge AS, Chen ZY (2008). "Hair cell regeneration". Curr Opin Neurobiol 18 (4): 377–82. doi:10.1016/j.conb.2008.10.001. PMID 18929656.
^ Lefèbvre P, Malgrange MB, Moonen MG (2008). "Regeneration of hair cells and auditory neurons in the ear". Bull Mem Acad R Med Belg 163 (7–9): 391–6. PMID 19445109.
^ Henderson M (2005-01-15). "Gene that may no longer turn a deaf ear to old age". Times Online.
^ Raphael Y, Martin DM (2005). "Deafness: Lack of regulation encourages hair cell growth". Gene Therapy 12 (13): 1021–22. doi:10.1038/sj.gt.3302523.
^ Löwenheim H, Furness DN, Kil J, Zinn C, Gültig K, Fero ML, Frost D, Gummer AW, Roberts JM, Rubel EW, Hackney CM, Zenner HP (1999-03-30). "Gene disruption of p27(Kip1) allows cell proliferation in the postnatal and adult organ of corti". Proc Natl Acad Sci U S A 96 (7): 4084–8. Bibcode:1999PNAS...96.4084L. doi:10.1073/pnas.96.7.4084. PMC 22424. PMID 10097167. (primary source)
^ Ono K, Nakagawa T, Kojima K, Matsumoto M, Kawauchi T, Hoshino M, Ito J (December 2009). "Silencing p27 reverses post-mitotic state of supporting cells in neonatal mouse cochleae". Mol Cell Neurosci 42 (4): 391–8. doi:10.1016/j.mcn.2009.08.011. PMID 19733668. (primary source)
^ Mizutari K, Fujioka M, Hosoya M, Bramhall N, et al. (2013). "Notch inhibition induces cochlear hair cell regeneration and recovery of hearing after acoustic trauma". Neuron 77 (1): 58–69. doi:10.1016/j.neuron.2012.10.032. PMC 3573859. PMID 23312516.

References

Coffin A, Kelley M, Manley GA, Popper AN. "Evolution of sensory hair cells". pp. 55–94. in Manley et al. (2004)
Fettiplace R, Hackney CM (2006). "The sensory and motor roles of auditory hair cells". Nature Reviews. Neuroscience 7 (1): 19–29. doi:10.1038/nrn1828. PMID 16371947.
Kandel ER, Schwartz JH, Jessell TM (2000). Principles of Neural Science (4th ed.). New York: McGraw-Hill. pp. 590–594. ISBN 0-8385-7701-6.
Manley GA, Popper AN, Fay RR (2004). Evolution of the Vertebrate Auditory System. New York: Springer-Verlag. ISBN 0-387-21093-8.
Manley GA. "Advances and perspectives in the study of the evolution of the vertebrate auditory system". pp. 360–368. in Manley et al. (2004)
Rabbitt RD, Boyle B, Highstein SM (1–5 February 2010). "Mechanical amplification by hair cells in the semicircular canals". Proceedings of the National Academy of Sciences 107 (8): 3864–9. doi:10.1073/pnas0906765107. PMC 2840494. PMID 20133682. Lay summary.
Breneman KD, Brownell WE, Rabbitt RD (22 April 2009). "Hair cell bundles: flexoelectric motors of the inner ear". In Brezina, Vladimir. PLOS One 4 (4): e5201. Bibcode:2009PLoSO...4.5201B. doi:10.1371/journal.pone.0005201. PMC 2668172. PMID 19384413. Lay summary.

External links

Molecular Basis of Hearing
Outer hair cell dancing "rock around the clock"
Dancing OHC video Yale Ear Lab
NIF Search - Hair Cell via the Neuroscience Information Framework
Hair-Tuning-Sound-Sensor A concise report on the recent development of sound sensors based on hair tuning by students of SMMEE, IIT Ropar

UpToDate Contents

全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.

1. 脱毛の評価および診断 evaluation and diagnosis of hair loss
2. 皮下蜂窩織炎様T細胞性リンパ腫の臨床症状、病理学的特徴、および診断 clinical manifestations pathologic features and diagnosis of subcutaneous panniculitis like t cell lymphoma
3. 進行期びまん性大細胞型B細胞性リンパ腫の初期治療 initial treatment of advanced stage diffuse large b cell lymphoma
4. 異型鎌状赤血球症候群 variant sickle cell syndromes
5. T細胞受容体シグナル伝達 t cell receptor signaling

English Journal

Immunolocalization of Wnt5a during the hair cycle and its role in hair shaft growth in mice.

Xing Y, Xu W, Yang K, Lian X, Yang T.SourceDepartment of Cell Biology, Third Military Medical University, Chongqing, People's Republic of China.
Acta histochemica.Acta Histochem.2011 Oct;113(6):608-12. Epub 2010 Jul 24.
Previous studies have shown that the Wnt signaling pathway plays an important role in the growth and development of hair follicles. It has been generally accepted that Wnt5a, a non-canonical Wnt gene, inhibits the Wnt/β-catenin signaling pathway. Several reports have addressed its mRNA expression i
PMID 20656336

Japanese Journal

歪成分耳音響放射(Distortion Product Otoacoustic Emission)の周波数特異性--純音聴力検査の聴力型との比較

安田真美子,枝松秀雄
東邦医学会雑誌 58(4), 268-276, 2011-07
NAID 40018920123

Related Pictures

★リンクテーブル★

リンク元	「外有毛細胞」「outer auditory hair cell」
関連記事	「outer」「out」「cell」

「外有毛細胞」

Neuron: PswiandfSW
	Section through the spiral organ of Corti. Magnified. ("Outer hair cells" labeled near top; "inner hair cells" labeled near center).
Location	Cochlea
Function	Amplify sound waves and transduce auditory information to the Brain Stem
Morphology	Unique (see text)
Presynaptic connections	None
Postsynaptic connections	Via auditory nerve to vestibulocochlear nerve to inferior colliculus
Gray's	p.1057
NeuroLex ID	nifext_61

　　[★]

英: outer hair cell
関: 有毛細胞

[show details]

外有毛細胞 : 約 19,100 件
外側有毛細胞 : 63 件

Henry Gray (1825-1861). Anatomy of the Human Body. 1918.

臨床関連

騒音性難聴

「outer auditory hair cell」

　　[★] 外有毛細胞 outer hair cell

「outer」

　　[★]

adj.

外側の

関: external、externally、lateral、laterale、lateralis、laterally、outside

「out」

　　[★] 　　　　　　　　　　　　　

「cell」

　　[★] 細胞　　　　　　　

[1] Müller, U (October 2008). "Cadherins and mechanotransduction by hair cells". Current opinion in cell biology 20 (5): 557–566. doi:10.1016/j.ceb.2008.06.004. PMC 2692626. PMID 18619539.

[2] Chan DK, Hudspeth AJ (February 2005). "Ca2+ current-driven nonlinear amplification by the mammalian cochlea in vitro". Nature Neuroscience 8 (2): 149–155. doi:10.1038/nn1385. PMC 2151387. PMID 15643426.

[3] Brownell WE, Bader CR, Bertrand D, de Ribaupierre Y (1985-01-11). "Evoked mechanical responses of isolated cochlear outer hair cells". Science 227 (4683): 194–196. Bibcode:1985Sci...227..194B. doi:10.1126/science.3966153. PMID 3966153.

[4] Wartzog D, Ketten DR (1999). "Marine Mammal Sensory Systems". In J. Reynolds, S. Rommel. Biology of Marine Mammals. Smithsonian Institution Press. p. 132.

[Hudspeth-5] Hudspeth AJ (2008-08-28). "Making an effort to listen: mechanical amplification in the ear". Neuron 59 (4): 530–45. doi:10.1016/j.neuron.2008.07.012. PMC 2724262. PMID 18760690.

[6] Santos-Sacchi Joseph, Song Lei, Zheng Jiefu, Nuttall Alfred L (2006-04-12). "Control of mammalian cochlear amplification by chloride anions". Journal of Neuroscience 26 (15): 3992–8. doi:10.1523/JNEUROSCI.4548-05.2006. PMID 16611815.

[7] "Cranial Nerve VIII. Vestibulocochlear Nerve". Meddean. Retrieved 2008-06-04.

[8] Edge AS, Chen ZY (2008). "Hair cell regeneration". Current Opinion in Neurobiology 18 (4): 377–82. doi:10.1016/j.conb.2008.10.001. PMID 18929656.

[9] st1=Forge, A; Li, L; Corwin, JT; Nevill, G (1993). "Ultrastructural evidence for hair cell regeneration in the mammalian inner ear". Science 259 (5101): 1616–9. Bibcode:1993Sci...259.1616F. doi:10.1126/science.8456284. PMID 8456284.

[10] Lefebvre first1=PP; Malgrange, B; Staecker, H; Moonen, G; Van De Water, TR (1993). "Retinoic acid stimulates regeneration of mammalian auditory hair cells". Science 260 (5108): 692–5. Bibcode:1993Sci...260..692L. doi:10.1126/science.8480180. PMID 8480180.

[11] Edge AS, Chen ZY (2008). "Hair cell regeneration". Curr Opin Neurobiol 18 (4): 377–82. doi:10.1016/j.conb.2008.10.001. PMID 18929656.

[12] Lefèbvre P, Malgrange MB, Moonen MG (2008). "Regeneration of hair cells and auditory neurons in the ear". Bull Mem Acad R Med Belg 163 (7–9): 391–6. PMID 19445109.

[13] Henderson M (2005-01-15). "Gene that may no longer turn a deaf ear to old age". Times Online.

[14] Raphael Y, Martin DM (2005). "Deafness: Lack of regulation encourages hair cell growth". Gene Therapy 12 (13): 1021–22. doi:10.1038/sj.gt.3302523.

[15] Löwenheim H, Furness DN, Kil J, Zinn C, Gültig K, Fero ML, Frost D, Gummer AW, Roberts JM, Rubel EW, Hackney CM, Zenner HP (1999-03-30). "Gene disruption of p27(Kip1) allows cell proliferation in the postnatal and adult organ of corti". Proc Natl Acad Sci U S A 96 (7): 4084–8. Bibcode:1999PNAS...96.4084L. doi:10.1073/pnas.96.7.4084. PMC 22424. PMID 10097167. (primary source)

[16] Ono K, Nakagawa T, Kojima K, Matsumoto M, Kawauchi T, Hoshino M, Ito J (December 2009). "Silencing p27 reverses post-mitotic state of supporting cells in neonatal mouse cochleae". Mol Cell Neurosci 42 (4): 391–8. doi:10.1016/j.mcn.2009.08.011. PMID 19733668. (primary source)

[17] Mizutari K, Fujioka M, Hosoya M, Bramhall N, et al. (2013). "Notch inhibition induces cochlear hair cell regeneration and recovery of hearing after acoustic trauma". Neuron 77 (1): 58–69. doi:10.1016/j.neuron.2012.10.032. PMC 3573859. PMID 23312516.

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案内

案内

outer hair cell