organ of Corti

コルチ器

WordNet

1. wind instrument whose sound is produced by means of pipes arranged in sets supplied with air from a bellows and controlled from a large complex musical keyboard (同)pipe_organ
2. a fully differentiated structural and functional unit in an animal that is specialized for some particular function
3. a government agency or instrument devoted to the performance of some specific function; "The Census Bureau is an organ of the Commerce Department"
4. a periodical that is published by a special interest group; "the organ of the communist party"

PrepTutorEJDIC

1. 『オルガン』,パイプオルガン(pipe organ),リードオルガン(reed organ),電子オルガン(electronic organ),手回しオルガン(barrel organ) / (動植物の)『器官』 / (政党・会社などの)機関誌,機関紙 / 《しばしば複数形で》(行動・実施などの)組織,機関
2. 《所有・所属》…『の』,…のものである,…に属する・《材料・要素》…『でできた』,から成る・《部分》…『の』[『中の』] ・《数量・単位・種類を表す名詞に付いて》…の・《原因・動機》…『で』,のために(because of) ・《主格関係》…『の』,による,によって・《目的格関係》…『を』,の・《同格関係》…『という』・《関係・関連》…『についての』[『の』],の点で・《抽象名詞などと共に》…の[性質をもつ] ・《『It is』+『形』+『of』+『名』+『to』 doの形で,ofの後の名詞を意味上の主語として》・《分離》…『から』・《起原・出所》…『から』[『の』](out of) ・《『名』+『of』+『a』(『an』)+『名』の形で》…のような・《『名』+『of』+『mine』(『yours, his』など独立所有格)の形で》…の…・《時》(1)《副詞句を作って》…に《形容詞句を作って》…の・《時刻》《米》…前(to,《米》before)
3. OLD French古[代]フランス語

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/07/28 13:23:11」(JST)

wiki en

[Wiki en表示]

Organ of Corti
A cross section of the cochlea illustrating the organ of Corti.
Details
Latin	organum spirale
Identifiers
Gray's	p.1056
MeSH	A09.246.631.246.577
Dorlands /Elsevier	12596269
TA	A15.3.03.121
FMA	75715
Anatomical terminology

The organ of Corti, or spiral organ, is the receptor organ for hearing and is located in the mammalian cochlea. Described as "a masterpiece of cellular micro-architecture", this highly varied strip of epithelial cells allows for transduction of auditory signals into nerve impulses' action potential. Transduction occurs through vibrations of structures in the inner ear causing displacement of cochlear fluid and movement of hair cells at the organ of Corti to produce electrochemical signals.

Italian anatomist Alfonso Giacomo Gaspare Corti (1822–1876) discovered the organ of Corti in 1851. The structure evolved from the Basilar papilla and is crucial for mechanotransduction in mammals.

Structure

The organ of Corti is located in the cochlea of the inner ear between the vestibular duct and the tympanic duct and is composed of mechanosensory cells, known as hair cells. Strategically positioned on the basilar membrane of the organ of Corti are three rows of outer hair cells (OHCs) and one row of inner hair cells (IHCs). Separating these hair cells are supporting cells: Deiters cells, also called phalangeal cells, which separate and support both the OHCs and the IHCs.

Projecting from the tops of the hair cells are tiny finger like projections called stereocilia, which are arranged in a gradated fashion with the shortest stereocilia on the outer rows and the longest in the center. This gradation is thought to be the most important anatomic feature of the organ of Corti because this allows the sensory cells superior tuning capability.

If the cochlea were uncoiled it would roll out to be about 33 mm long in women and 34mm in men, with about 2.28 mm of standard deviation for the population. The cochlea is also tonotopically organized, meaning that different frequencies of sound waves interact with different locations on the structure. The base of the cochlea, closest to the outer ear, is the most stiff and narrow and is where the high frequency sounds are transduced. The apex, or top, of the cochlea is wider and much more flexible and loose and functions as the transduction site for low frequency sounds.

Function

The function of the organ of Corti is to transduce auditory signals and maximize the hair cells’ extraction of sound energy. It is the auricle and middle ear that act as mechanical transformers and amplifiers so that the sound waves end up with amplitudes 22 times greater than when they entered the ear.

Auditory transduction

For auditory signals to reach the organ of Corti in the first place, they must come from the outer ear. Sound waves enter through the auditory canal and vibrate the tympanic membrane, also known as the eardrum, which vibrates three small bones called the ossicles. As a result, the attached oval window moves and causes movement of the round window, which leads to displacement of the cochlear fluid. .

The basilar membrane on the tympanic duct presses against the hair cells of the organ as perilymphatic pressure waves pass. The stereocilia atop the IHCs move with this fluid displacement and in response their cation, or positive ion selective, channels are pulled open by cadherin structures called tip links that connect adjacent stereocilia. The organ of Corti lies on the basilar membrane at the base of the scala media and is surrounded by endolymph, a potassium rich fluid. Under the organ of Corti is the scala tympani and above it is the scala vestibuli, both structures exist in a low potassium fluid called perilymph. Because those stereocilia are in the midst of a high concentration of potassium, once their cation channels are pulled open potassium ions as well as calcium ions flow into the top of the hair cell. With this influx of positive ions the IHC becomes depolarized, opening voltage-gated calcium channels at the basolateral region of the hair cells and triggering the release of the neurotransmitter glutamate. An electrical signal is then sent through the auditory nerve and into the auditory cortex of the brain as a neural message.

Cochlear amplification

The organ of Corti is also capable of modulating the auditory signal. The OHCs can amplify the signal through a process called electromotility where they increase movement of the basilar membrane and therefore increase deflection of stereocilia in the IHCs. Through its association with the tectorial membrane, motion of the basilar membrane can enhance vibrations in the cochlea.

A crucial piece to this cochlear amplification is the motor protein prestin, which changes shape based on the voltage potential inside of the hair cell. When the cell is depolarized prestin shortens, and because it is located on the membrane of OHCs it then pulls on the basilar membrane and increasing how much the membrane is deflected, creating a more intense effect on the IHCs. When the cell hyperpolarizes prestin lengthens and eases tension on the IHCs, which decreases the neural impulses to the brain. In this way, the hair cell itself is able to modify the auditory signal before it even reaches the brain.

Development

The organ of Corti develops between the scala tympani and the scala media after the formation ad growth of the cochlear duct. Next, the inner and outer hair cells differentiate into their appropriate positions, followed by the organization of the supporting cells. The topology of the supporting cells lends itself to the actual mechanical properties that are needed for the organ of Corti’s specialized sound-induced movements.

Development and growth of the organ of Corti relies on specific genes, many of which have been identified in previous research (SOX2, GATA3, EYA1, FOXG1, BMP4, RAC1 and more) Some genes required for the organ of Corti are also important for the differentiation of the cochlear duct and are required for its growth and for the formation of hair cells in the organ of Corti specifically.

Mutations in the genes expressed in or near the organ of Corti before the differentiation of hair cells will result in a disruption in the differentiation, and potential malfunction of, the organ of Corti.

Clinical significance

Hearing loss

Main article: Hearing impairment

The organ of Corti can be damaged by excessive sound levels, leading to noise-induced impairment.

The most common kind of hearing impairment, sensorineural hearing loss, includes as one major cause the reduction of function in the organ of Corti. Specifically, the active amplification function of the outer hair cells is very sensitive to damage from exposure to trauma from overly-loud sounds or to certain ototoxic drugs. Once outer hair cells are damaged, they do not regenerate, and the result is a loss of sensitivity and an abnormally large growth of loudness (known as recruitment) in the part of the spectrum that the damaged cells serve.

While hearing loss has always been considered irreversible in mammals, fish and birds routinely repair such damage. A 2013 study has shown that the use of particular drugs may reactivate genes normally expressed only during hair cell development. The research was carried out at Harvard Medical School, the Massachusetts Eye and Ear Infirmary, and the Keio University School of Medicine in Japan.

Additional images

• Transverse section of the cochlear duct of a fetal cat.

• Diagrammatic longitudinal section of the cochlea.

• Floor of ductus cochlearis.

• Limbus laminæ spiralis and membrana basilaris.

• Section through the spiral organ of Corti. Magnified.

Notes

References

• Corti, A. (1851). Recherches sur l’organe de l'ouïe des mammiferes. Zeitschrift Für Wissenschaftliche Zoologie, 3, 106–169.
• Fritzsch, B., Jahan, I., Pan, N., Kersigo, J., Duncan, J., & Kopecky, B. (2012). Dissecting the molecular basis of organ of Corti development: where are we now? Hearing Research, 276(1-2), 16–26.

History. (n.d.).

• Hudspeth, A. (2014). Integrating the active process of hair cells with cochlear function. Nature Reviews Neuroscience, 15, 600–614.
• Lim, D. (1986). Functional structure of the organ of Corti: a review. Hearing Research, 22, 117–146.
• Malgrange, B., Thiry, M., Van de Water, T. R., Nguyen, L., Moonen, G., & Lefebvre, P. P. (2002). Epithelial supporting cells can differentiate into outer hair cells and Deiters’ cells in the cultured organ of Corti. Cellular and Molecular Life Sciences, 59(10), 1744–1757. doi:10.1007/PL00012502
• Nicholls, J. G., Martin, A. R., Fuchs, P. A., Brown, D. A., Diamond, M. E., & Weisblat, D. A. (2012). From Neuron to Brain (5th ed., pp. 456–459). Sunderland, MA: Sinauer Associates, Inc.
• Pritchard U. "On the organ of Corti in mammals". 2 March 1876, Proceedings of the Royal Society of London, volume 24, pp. 346–52 OCLC 1778190
• Pujol, R., & Irving, S. (2013). The Ear.

External links

• Dissecting the molecular basis of organ of Corti development
• Organ of Corti 3D animation
• http://lobe.ibme.utoronto.ca/presentations/OHC_Electromotility/sld005.htm Diagram at University of Toronto
• http://mayoresearch.mayo.edu/mayo/research/ent_research/images/image02.gif Diagram at Mayo
• http://www.iurc.montp.inserm.fr/cric51/audition/english/corti/fcorti.htm at University of Montpellier 1

UpToDate Contents

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English Journal

• Time evolution of noise induced oxidation in outer hair cells: Role of NAD(P)H and plasma membrane fluidity.

• Maulucci G1, Troiani D2, Eramo SL3, Paciello F4, Podda MV3, Paludetti G4, Papi M1, Maiorana A1, Palmieri V1, De Spirito M1, Fetoni AR4.
• Biochimica et biophysica acta.Biochim Biophys Acta.2014 Jul;1840(7):2192-202. doi: 10.1016/j.bbagen.2014.04.005. Epub 2014 Apr 13.
• BACKGROUND: Noise exposure impairs outer hair cells (OHCs). The common basis for OHC dysfunction and loss by acoustic over-stimulation is represented by reactive oxygen species (ROS) overload that may affect the membrane structural organization through generation of lipid peroxidation.METHODS: Here
• PMID 24735797

• Alpha-lipoic acid protects against cisplatin-induced ototoxicity via the regulation of MAPKs and proinflammatory cytokines.

• Kim J1, Cho HJ2, Sagong B1, Kim SJ3, Lee JT4, So HS3, Lee IK5, Kim UK6, Lee KY7, Choo YS1.
• Biochemical and biophysical research communications.Biochem Biophys Res Commun.2014 Jun 27;449(2):183-9. doi: 10.1016/j.bbrc.2014.04.118. Epub 2014 May 2.
• Cisplatin is an effective antineoplastic drug that is widely used to treat various cancers; however, it causes side effects such as ototoxicity via the induction of apoptosis of hair cells in the cochlea. Alpha-lipoic acid (ALA) has been reported to exert a protective effect against both antibiotic-
• PMID 24796665

• Role of cysteinyl leukotriene signaling in a mouse model of noise-induced cochlear injury.

• Park JS1, Kang SJ2, Seo MK3, Jou I2, Woo HG3, Park SM4.
• Proceedings of the National Academy of Sciences of the United States of America.Proc Natl Acad Sci U S A.2014 Jun 23. pii: 201402261. [Epub ahead of print]
• Noise-induced hearing loss is one of the most common types of sensorineural hearing loss. In this study, we examined the expression and localization of leukotriene receptors and their respective changes in the cochlea after hazardous noise exposure. We found that the expression of cysteinyl leukotri
• PMID 24958862

Japanese Journal

• Ceramide/sphingomyelin cycle involvement in gentamicin-induced cochlear hair cell death

• Archives of
• NAID 120005604022

• Optical Coherence Tomography による蝸牛内部構造の観察

• Equilibrium Research 74(4), 313-317, 2015
• NAID 130005101951

• 環境ストレスと関連する聴覚系疾患の解析

• 日本衛生学雑誌 70(2), 100-104, 2015
• NAID 130005070847

Related Links

• Organ of Corti - Wikipedia, the free encyclopedia

The organ of Corti (or spiral organ) is the organ in the inner ear found only in mammals that contains auditory sensory cells, or "hair cells." The organ was named after the Italian anatomist Marquis Alfonso Giacomo Gaspare Corti (1822 –1876), ...

Related Pictures

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★リンクテーブル★

リンク元	「聴覚」「コルチ器」「コルチ器官」「コルティ器官」「basilar papilla」
関連記事	「organ」

「聴覚」

　　[★]

英

audition, hearing

同

聴感覚

• 音

• 圧変動(振動:縦波)の終発

• 単位

• dB = 20 log10 (被験音圧)/(基準音圧)

• 可聴域

• 20Hz-20kHz (20-20000)

• 検知閾

• 1kHzで最低

• 会話言語域

• 100Hz-4kHz

聴覚の受容器

• 1. 外耳

集音・共振による音圧増強: 20dB

• 耳介
• 外耳道
• 鼓膜
• 2. 中耳

鼓膜面積：アブミ骨底面積比と耳小骨連鎖のてこ比による音圧増強: 27dB

• ツチ骨
• キヌタ骨
• アブミ骨

• 3. 内耳

• 蝸牛器官

蝸牛器官の構造

• 前庭階

• ライスネル膜

• 中央階

• コルチ器
• 血管条
• 基底膜

基底膜の幅・柔らかさ・外有毛細胞による伸縮作用が異なる。

前庭階の入り口に近い基底膜が高周波数に応じて振動する (SP.240)

• 鼓室階

基底膜振動の伝播と進行波

• 進行波

SP. 　基底膜振動の伝播は進行波と呼ばれる。

• 周波数同調

-周波数同調特性
SP. 240,251,252
-同調曲線
SP. 240,250,251 
-特徴周波数
SP. 240,250

• 同調曲線上で、応答の閾値が最小値をとる周波数はその系が最も応答しやすい周波数(=特徴周波数)となる。

-周波数帯域
周波数帯SP. 239
-周波数局在性
SP. 202,206,241,250,258,260 

• 振動周波数が高くなるに従い、振動の頂点は蝸牛管基部に生じる
• 蝸牛器官、らせん神経節、蝸牛神経核、上オリーブ核、台形体核、外側毛帯核、下丘、内側膝状体、聴皮質はすべて周波数局在性を有する(SP.250)

コルチ器 (2007年後期生理学授業プリント)

蝸牛基底部から頂部に至るらせん状の構造を全体として形成する

• 内有毛細胞 inner hair cell

• 蝸牛の回転の内側に配列する
• 1列
• 3500個/蝸牛
• 感覚毛(不動毛。×動毛)
• 受容器細胞として主役
• 求心線維の90-95%が分布

• 内柱細胞 inner pillar cell
• コルチのトンネル tunnel of Corti
• 外柱細胞 outer pillar cell
• 外有毛細胞 outer hair cell

SP. 240-243,245-252,259

• 蝸牛の回転の外側に配列する
• 3-4列
• 20000個/蝸牛
• 感覚毛(不動毛。×動毛)
• 遠心性細胞が分布
• 膜電位に応じて長さを変化させ、基底膜同調特性に非線形的な増強を与えると考えられている。

• ダイテルス細胞 Deiters cell

• 外有毛細胞を支持

• ヘンゼン細胞 Hensen cell
• 網状板(=網様膜)
• 蓋膜
• 蝸牛神経線維

• 遠心性線維(蝸牛神経節経由)
• 求心性線維(上オリーブ核(延髄)由来)

• らせん神経節 spiral ganglion

• 疑似双極細胞

受容器電位 receptor potential

SP. 50,185,219,220,243

• 受容器電位の発生から聴神経におけるインパルス発生まで

• 1. 有毛細胞の感覚毛屈曲
• 2. 有毛細胞における受容器電位の発生
• 3. 有毛細胞から求心性線維への神経伝達物質（グルタミン酸）放出
• 4. 求心性線維終末におけるEPSP発生
• 5. 求心性線維終末における活動電位の発生

蝸牛マイクロフォン電位 cochlear microphonics potential, CM

SP. 247

聴覚刺激を与えることで、内耳および内耳周辺では刺激をを忠実に反映した電気信号が記録される。この電位をマイクロホン電位と呼ぶ(SP.247)

• 蝸牛マイクロフォン電位は感覚毛の振動で生じた受容器電位の総和(PT.163)

内リンパ腔電位 endolymph potential (=蝸牛内直流電位)

SP. 246,247

難聴

• 伝音性難聴

• 伝音性難聴とは、伝音機能の不良（音の伝達不良）によって起こる難聴であり、鼓膜破損や耳小骨硬化、慢性中耳炎などで起こり、骨伝導には問題がない。低音域で障害があらわれ、補聴器で補正できる。

• 感音性難聴

• 感音性難聴とは、音の受容に問題があって起こる難聴であり、コルチ器官や聴神経あるいは聴神経核などの障害、利尿剤・老化による有毛細胞の変性などで起こる。高音域で障害があらわれ、補聴器で補正できない。

聴覚の伝導路

SP. 254-

• 1. 蝸牛・コルチ器官・有毛細胞
• 2. 蝸牛神経線維
• 3. らせん神経節(=蝸牛神経節) [一次ニューロン]
• 4. 蝸牛神経核 cochlear nucleus
• 5. 上オリーブ核群
• 6. 台形核
• 7. 外側毛帯
• 8. 外側毛体格
• 9. 下丘
• 10. 内側膝状体
• 11. 視床枕・網様核
• 12. 大脳皮質第一次聴覚野
• 13. 大脳皮質聴覚連合野
• 14. 大脳皮質感覚性言語中枢

(Q.book p.107)

• organ of Corti -> spiral ganglion in the cochlea -> vestibulocochlear nerve(CN VIII) -> cochlear nuclei(dorsal and ventral) -> superior olivary nuclei -> lateral lemniscus -> inferior colliculus -> medial geniculate nucleus of the thalamus(MGN) -> primary auditory cortex(Heschl's gyrus)

伝導路における交叉

• 交叉は台形体・下丘で行われるが、反対皮質の優位性は低い
• 聴覚は両側性に中枢に伝わる
• 4-6個のニューロンを比較的多数のシナプスを中継して中枢に至る

「コルチ器」

　　[★]

英

organ of Corti, Corti's organ

ラ

organum spirale Cortii

同

ラセン器 spiral organ organum spirale

関

聴覚受容器、蝸牛

「コルチ器官」

　　[★]

英

organ of Corti

関

乳頭基部、コルチ器、コルティ器官

「コルティ器官」

　　[★]

英

organ of Corti

関

コルチ器官、コルチ器

「basilar papilla」

　　[★]

乳頭基部

関

organ of Corti

「organ」

　　[★]

• n.

• 臓器、器官