胚胎小鼠耳蜗感觉上皮的形态发生

目的了解胚胎小鼠耳蜗感觉上皮发育的形态学特征及规律。方法利用光镜、扫描电镜、透射电镜观察从胚胎第8天到刚出生期间C57BL/6小鼠耳蜗感觉上皮发育过程中的形态变化。结果C57BL/6小鼠胚胎第10.5天耳蜗开始发育,感觉上皮由高柱状上皮细胞组成,到胚胎第14天才开始分化为原始的毛细胞;胚胎第16天耳蜗底转Corti器原基形成,毛细胞和支持细胞初具雏形;到出生时,耳蜗形态基本成熟,但底转Corti器仅趋向成熟,蜗尖才形成Corti器原基。结论小鼠耳蜗感觉上皮发育的形态变化在胚胎第13天到出生时最明显,感觉细胞都来源于一种高柱状上皮细胞,到胚胎第14天开始分化为毛细胞;而Corti器的分化成熟是从底转向顶转进行的,出生时尚未完全发育成熟。     

大鼠内耳Corti氏器扫描电镜样品的制备与观察

本文首次报告非脱钙的大鼠耳蜗Corti氏器扫描电镜样品制备方法,观察和测量了听毛细胞静纤毛及其表面结构。结果表明,经本方法制备的样品,Corti器表面超微结构保存良好,显示清晰。大鼠耳蜗可根据外毛细胞静纤毛特点分为顶、中、底三个区域。本文认为,以Corti氏器表面超微结构特征为标志的耳蜗分区法对于研究和分析听毛细胞的生理功能及其病理改变具有重要意义。     

听力学

88030876 大鼠内耳Corti氏器扫描电镜样品的制备与观察/孙爱华…∥临床耳鼻咽喉科杂志.-1987,1(4).-205～207 本文首次报告非脱钙的大鼠耳蜗Corti氏器扫描电镜样品制备方法,观察和测量了听毛细胞静纤毛及其表面结构。结果表明,经本方法制备的样品,Corti器表面超微结构保存良好,显示清晰。大鼠耳蜗可根据外毛细胞静纤毛特点分为顶、中、底三个区域。本文认为,以Corti氏器表面超微结构特征为标志的耳蜗分区法对于研究和分析听毛细胞的生理功能及其病理改变     

斯里兰卡肉桂碱受体在不同鼠龄大鼠耳蜗中的表达差异

目的 研究不同鼠龄大鼠耳蜗内斯里兰卡肉桂碱受体(ryanodine receptor,RyR)的差异表达.探讨RyR表达与耳蜗发育成熟的关系.方法 分别选取出生后1天(P1)、5天(P5)、10天(P10)、14天(P14)、28天(P28)以及成年SD大鼠(＞2月龄)各5只耳蜗作冰冻切片.运用免疫荧光的方法 ,比较各组大鼠耳蜗组织RyR的表达差异.结果 P1组和P5组大鼠耳蜗Corti器内RyR表达不明显,P10组出现的RyR染色均匀,而P14组大鼠耳蜗Corti器内RyR的表达出现明显特征性变化,毛细胞突触区RyR强表达,而支持细胞内的表达相对较为广泛.大鼠出生后耳蜗螺旋神经元内RyR的表达由广泛的胞内表达,逐渐趋近细胞膜突触区.结论 RyR在大鼠出生后14天表达基本成熟,与耳蜗的发育成熟基本保持一致.感觉毛细胞和螺旋神经元的RyR表达可能与神经传递等功能相关.在发育早期的螺旋神经元细胞中RyR的广泛表达,可能参与了螺旋神经元发育成熟中的细胞凋亡过程.     

新霉素致发育中大鼠毛细胞损伤的电镜观察

目的应用扫描电镜研究氨基甙类抗生素导致出生后发育过程中大鼠耳蜗毛细胞的损伤病理变化。方法７天龄ＳＤ大鼠肌肉注射８０ｍｇｋｇ－１ｄ－１新霉素连续８天,停药后７天处死动物制备样本进行扫描电镜观察。结果新霉素可造成出生后发育过程中的耳蜗毛细胞严重损伤,表现为底回和钩回三排外毛细胞全部损伤缺失,损伤病变累及顶回的外毛细胞,底回和钩回的内毛细胞出现纤毛脱落和细胞损伤丢失;外毛细胞损伤缺失的部位由顶部具有微绒毛的多边形细胞取代,该细胞形态与胚胎发育早期的毛细胞相似;毛细胞损伤区域未发现再生的毛细胞。结论出生后发育过程中大鼠耳蜗毛细胞对氨基甙类抗生素的敏感性较高,表面有微绒毛的多边形细胞在毛细胞损伤区域出现提示听觉感觉上皮细胞有再生的倾向。     

人Corti‘s器扫描电镜观察

目的 了解正常人Corti’s器的超微结构特征。方法 用扫描电镜观察成年人和胎儿的Corti’s器。结果成人和胎儿Corti’s器基底圈内、外毛细胞排列规则,中圈和顶圈毛细胞排列不规则,内毛细胞以一排,外毛细胞以三排排列。可观察到列外的内、外毛细胞,四排排列和自然缺失的外毛细胞。外毛细胞粗大的静纤毛以及由于固定不及时引起的外毛细胞静纤毛气球样改变。结论 用扫描电镜观察成人和胎儿Corti’s器的精细结构,发现了毛细胞排列的基本规律和一些异常的形态。及时固定是保存Corti’s器结构完好的必要条件。     

细胞增殖及凋亡与耳蜗感觉上皮的分化

目的观察耳蜗发育中细胞增殖、凋亡的变化规律，探讨它们与耳蜗感觉上皮分化的关系。方法利用透射电镜观察从胚胎第8天到刚出生的C57BL/6小鼠耳蜗感觉上皮的增殖、凋亡及分化的变化。结果胚胎第10天，耳蜗才开始发育；到胚胎第11天耳蜗感觉上皮出现核分裂像并逐渐增多，胚胎第14天时已开始减少；细胞凋亡现象出现在胚胎第13天，从胚胎第14天到胚胎第15天细胞凋亡最明显，后逐渐减少；同时在胚胎第14天毛细胞开始分化形成，到胚胎第16天，Corti器原基形成时，毛细胞和支持细胞形态趋向成熟，但到出生时，Corti器尚未发育成熟。结论细胞增殖和凋亡是耳蜗发育中的必然现象，细胞增殖、凋亡及毛细胞的分化成熟相继发生但又互相重叠；细胞增殖与凋亡的动态平衡在耳蜗感觉上皮分化成熟中起着重要作用。     

大鼠耳蜗发育过程中生存素和半胱氨酸天冬氨酸蛋白酶3的表达

目的 探讨大鼠耳蜗形态学发育过程中凋亡相关因素的作用.方法 通过免疫组化蛋白定位以及逆转录-聚合酶链反应(RT-PCR)技术检测生存素(survivin)和半胱氨酸天冬氨酸蛋白酶3(easpase-3)在胚胎期及出生后Wistar大鼠耳蜗中的表达情况.结果 survivin和caspase-3在细胞增殖期广泛表达于即将分化发育形成Corti器的蜗管底壁,在细胞分化期表达逐渐增强;survivin在细胞分化末期达到高峰,持续到细胞发育成熟期开始之后下降,在成熟的corti器毛细胞中仍有较强表达;而caspase-3在细胞发育成熟期开始时达到高峰,以后逐渐下降,直至表达消失.结论 survivin和caspase-3在大鼠耳蜗发育过程中表达范围相似,但表达量在时间上并不同步,survivin的表达高峰早于caspase-3,二者相互作用共同调控细胞凋亡,促进耳蜗形态结构的成熟.     

早期气导听觉剥夺对幼鼠听觉发育的影响

目的研究早期气导听觉剥夺对大鼠听性脑干反应(ABR)和Corti器基底膜发育的影响。方法 SD仔鼠共60只,随机分为听觉剥夺组及对照组,每组30只。听觉剥夺组行双外耳道填塞后饲养于密闭隔声室,对照组在正常声音环境饲养,两组动物分别于出生后21、28、35、42及56天时行ABR检测,42及56天时应用扫描电镜观察Corti器基底膜发育情况。结果对照组大鼠ABR反应阈随年龄增长呈下降趋势,56天时为24.17 dB SPL,基本达到正常成年大鼠水平,听觉剥夺组大鼠随饲养时间延长ABR反应阈较对照组明显增高,35天时增高至39.47 dB SPL,去除双外耳道填塞物后ABR反应阈无明显恢复。扫描电镜可见对照组Corti器基底膜外毛细胞纤毛排列整齐,听觉剥夺组基底膜外毛细胞表面形成大量细小囊泡,纤毛末端膨大、融合。结论出生后早期气导听觉剥夺可造成大鼠Corti器基底膜发育异常以及听觉障碍,表明气导听觉传入在听觉发育过程中起着十分重要的作用。     

大鼠耳蜗发育过程中突触素的表达差异

目的 研究大鼠耳蜗发育过程中突触素(synaptophysin,SYN)的表达差异,探讨SYN表达与听觉功能发育成熟的关系及耳蜗中三磷酸腺苷(adenosine triphosphate,ATP)的来源.方法 选取健康SD大鼠25只,按出生后天数将其分为出生后1、5、10、14、28天组(即:P1、P5、P10、P14和P28组),每组5只,运用免疫组化的方法比较各组大鼠耳蜗中SYN的表达差异.结果 P1、P5和P10组大鼠顶回的Corti器、Kolliker器未发现SYN表达;P10组底回及蜗管中段、P14组和P28组Corti器的内、外螺旋束、Deiters细胞内侧缘有特异性表达;各组大鼠耳蜗螺旋神经元(spiral ganglion neuron,SGN)胞浆中均有SYN表达.结论 大鼠耳蜗发育过程中SYN的表达存在差异,这种差异有利于神经末梢和靶细胞间构型建立,对听觉系统发育中形成正确的听觉信息编码可能起着关键作用.毛细胞、支持细胞中的ATP可能以非囊泡或以非SYN特异性染色的囊泡形式储存.     

Deiters cells tread a narrow path--the Deiters cells-basilar membrane junction

Deiters cells extend from the basilar membrane to the reticular lamina and, together with pillar cells and outer hair cells, structurally define the micro-architecture of the organ of Corti. Studying vibrotome sections of the mouse organ of Corti with confocal and scanning electron microscopy we found that the basal pole of every Deiters cell, independently of their position in the organ of Corti and along the cochlear spiral, attached to the basilar membrane within a 15.1?±?0.3?μm-wide stripe running the length of the cochlear spiral adjacent to the row of outer pillar cells. All Deiters cells' basal poles had similar diameter and general morphology, and distributed on the stripe in a precise arrangement with a center-to-center distance of 7.1?±?0.3?μm between neighbor cells of the same row and 5.9?±?0.4?μm for neighbor cells in adjacent rows. Complete detachment of Deiters cells revealed an elliptical imprint on the top surface of the basilar membrane consisting of a smaller central structure with a very smooth surface surrounded by a rougher area, suggesting the presence of two different anchoring junctions. These previously unidentified morphological features of Deiters cells could be critical for the mechanical response of the organ of Corti.     

Epidermal Growth Factor Upregulates Production of Supernumerary Hair Cells in Neonatal Rat Organ of Corti Explants

The organ of Corti is highly ordered, with a single row of inner hair cells and three rows of outer hair cells. The number of hair cells produced was thought to be limited by the time of their terminal mitosis (i.e. E14 in the mouse). However, exogenous application of retinoic acid has been shown to stimulate the formation of supernumerary hair cells in organ of Corti explants from E13 to E16 mouse embryos. Using late embryonic and neonatal rat organ of Corti explants, we investigated the potential for production of supernumerary hair cells in more mature auditory sensory epithelia. When newborn rat organ of Corti explants were cultured under control conditions, an area of supernumerary hair cells was observed in a segment of organ of Corti that was at the junction between the basal and middle turns. In these areas of supernumerary hair cells the number of hair cells increased per unit of length, but remained constant per surface unit, further demonstrating the supernumerary character of this phenomenon. Organ of Corti explants treated with epidermal growth factor (EGF) showed a 50% increase in the length of the organ of Corti segment containing supernumerary hair cells. Upregulation of supernumerary hair cell formation by EGF was found to start and be maximal at birth (P0) and to disappear by 2 days after birth (P2). Treatment of EGF stimulated P0 explants with an antimitotic drug, cytosine arabinoside (ARAc), demonstrated that the production of supernumerary hair cells occurred independently of cell division.     

Epidermal growth factor upregulates production of supernumerary hair cells in neonatal rat organ of corti explants

The organ of Corti is highly ordered, with a single row of inner hair cells and three rows of outer hair cells. The number of hair cells produced was thought to be limited by the time of their terminal mitosis (i.e. E14 in the mouse). However, exogenous application of retinoic acid has been shown to stimulate the formation of supernumerary hair cells in organ of Corti explants from E13 to E16 mouse embryos. Using late embryonic and neonatal rat organ of Corti explants, we investigated the potential for production of supernumerary hair cells in more mature auditory sensory epithelia. When newborn rat organ of Corti explants were cultured under control conditions, an area of supernumerary hair cells was observed in a segment of organ of Corti that was at the junction between the basal and middle turns. In these areas of supernumerary hair cells the number of hair cells increased per unit of length, but remained constant per surface unit, further demonstrating the supernumerary character of this phenomenon. Organ of Corti explants treated with epidermal growth factor (EGF) showed a 50% increase in the length of the organ of Corti segment containing supernumerary hair cells. Upregulation of supernumerary hair cell formation by EGF was found to start and be maximal at birth (P0) and to disappear by 2 days after birth (P2). Treatment of EGF stimulated P0 explants with an antimitotic drug, cytosine arabinoside (ARAc), demonstrated that the production of supernumerary hair cells occurred independently of cell division.     

Tubulin expression in the developing and adult gerbil organ of Corti

In the late stages of inner ear development, the relatively undifferentiated cells of Kollicker's organ are transformed into the elaborately specialized cell types of the organ of Corti. Microtubules are prominent features of adult cells in the organ of Corti, particularly supporting cells. To test the possible role of microtubules in organ of Corti development, the microtubule organization in the organ of Corti has been examined using indirect immunofluorescence to beta-tubulin in the developing gerbil cochlea. Tubulin first appears at post-natal day 0 (P0) as filamentous asters in inner hair cells and by P2, asters are also seen in outer hair cells. Tubulin appears at P3 in inner pillar cells in a tooth crown-like figure. By P6, tubulin expression is also evident in outer pillar cells and by P9, it is seen in Deiters cells. Elaboration of microtubules in pillar cells was observed to proceed from the reticular lamina towards the basilar membrane. The pattern of tubulin expression in the apical organ of Corti lags the base by about 3 days until P6, but by P9, apical and basal organ of Corti appear substantially the same.     

Repair pattern of the reticular lamina of the organ of corti in human ears

The repair pattern of the reticular lamina of the organ of Corti was studied in the cochleae of human ears. The inner ears were obtained at autopsy from the individuals who had no evidence of auditory or vestibular disorders or therapy with ototoxic drugs:

• After a loss of outer or inner hair cells, the framework of the reticular lamina was distorted but no gaps were detected. The supporting cells were hypertrophied but no reparative proliferation of the supporting cells was found in the organ of Corti.
• Defects due to the collapse of outer hair cells of the first row were filled in mainly by the hypertrophied heads of the outer pillar cells.
• Defects due to the collapse of outer hair cells of the second, third and fourth row were filled in mainly by the hypertrophied phalanges of Deiters' cells of the first, second and third row respectively.
• The space due to inner hair cell loss was filled in by the nearest inner supporting cells which were hypertrophied and extended toward the space.
• The distortion of the reticular lamina and the aging degeneration were regarded as two possible causes for the total loss of the organ of Corti near the end of the first turn.

     

High resolution scanning electron microscopy of the human organ of Corti. A study using freshly fixed surgical specimens

Scanning electron microscopy on immediately fixed human cochleae obtained during surgery for life-threatening petro-clival meningioma showed excellently preserved morphology. We compared the morphological findings with those from transmission electron microscopic sections of well preserved human and animal tissue. The characteristics of neural innervation, the pathways of the nerves through the organ of Corti and the intimate relation of nerves to supporting cells along their route could be studied in detail. The lateral membranes of Hensen and Claudius cells were folded creating a surface enlargement. Marginal pillars extended the distal end of the tectorial membrane and correspond to the marginal net or "randfasernetz" described earlier. Stereocilia imprints at the undersurface of the tectorial membrane go as far as to the distal end of the marginal pillars. The presence of an irregularly distributed fourth row of outer hair cell, attached to the marginal pillars, raises questions about differences in the excitation of the last row of outer hair cells. The complex nature of many supporting cells, stria vascularis and Reissner's membrane, intracellular complexities as well as surface features are described. Supernumerary inner hair cells were observed and the different arrangement of outer spiral fibres in contrast to findings in animals and variations of nerve fibres within the organ of Corti between apex and base are discussed.     

Localization of the P2Y4 receptor in the guinea pig organ of Corti

Cochleae of guinea pigs were evaluated for the presence of the metabotropic receptor, P2Y4. Evidence is presented that P2Y4 protein is expressed in the guinea pig cochleae using Western blot analysis. A single protein band of 35 kDa was detected with P2Y4 receptor-specific antibody. The cellular distribution of P2Y4 purinoceptor protein was determined by immunohistochemistry of the whole organ of Corti. Immunoreactive staining for P2Y4 was seen in most cells of the organ of Corti. Staining of Hensen's cells and Deiters' cells, especially the outer Deiters' cells, was more intense than staining of the outer hair cells, inner hair cells, and pillar cells. Staining intensity was greatest at the basal turn and progressively decreased in the upper turns with the apex showing the weakest staining pattern. This is the first demonstration of a metabotropic P2Y receptor in the guinea pig organ of Corti.     

Supernumerary outer hair cells arise external to the last row of sensory cells in the organ of corti

During the development of the mammalian inner ear, the number of hair cells produced is highly regulated and remains constant throughout life. The mechanism underlying this regulation is beginning to be understood although many aspects still remain obscure. When late embryonic or early postnatal rat organs of Corti were cultured, the production of supernumerary hair cells was observed. This overproduction of sensory cells could be modulated by the addition of several growth factors. In this study, we examined explants of rat organs of Corti that produced supernumerary hair cells. In the supernumerary hair cell region, up to two rows of inner hair cells and five rows of outer hair cells were observed. Morphological evaluation of these specimens revealed that less mature hair cells were located in the most external rows of these sensory cells. When a supernumerary hair cell was produced, a supporting cell (i.e. Deiters' cell) was also produced, strongly suggesting that the conversion of a Deiters' cell into a hair cell was not the mechanism that produced these extra hair cells. Based on these results, we propose that prosensory cells located at the external edge of the organ of Corti retain a capacity to form hair cells and that it is these prosensory cells that differentiate into supernumerary hair cells and Deiters' cells.     

SD大鼠损伤Corti器中毛细胞样细胞的演变

目的：研究氨基糖类抗生素引起哺乳类动物Corti器损伤及损伤后的修复情况。方法：用新霉素皮下注射致新生SD大鼠Corti器损伤，然后用扫描电镜观察停药后不同时期的Corti器毛细胞的损伤及修复表现。结果：在外毛细胞损伤区有细胞表面长有微绒毛簇的毛细胞样细胞出现，且其在损伤Croti器中有发生-发展-退化的变化过程。结论：毛细胞样细胞的出现是受损伤Corti器的一种修复形式。