内毛细胞的分离和形态学特点

目的　探讨内毛细胞 (innerhaircells ,IHC)的分离技术和形态学特征。方法　从豚鼠耳蜗制备基底膜活体铺片 ,微分干涉倒置显微镜下用显微分离结合酶消化的方法单离IHC。高倍显微镜下 ,用两个钨丝电极沿IHC和第一排外毛细胞 (outerhaircells,OHC)之间的Corti隧道显微切割 ,游离的IHC团被吸引至玻璃微吸管内。结果　从每只豚鼠耳蜗可分离到 3 0～ 5 0个活性良好的单离IHC ,并存活 2h左右。典型的IHC胞体具有特征性 ,呈梨状或长颈的烧瓶形状 ,胞体中间可见大的圆形细胞核。胞体内包含较多细胞器 ,颗粒状 ,粗糙感。大部分可观察到静纤毛 ( 93 / 98)。静纤毛分布沿表皮板一侧 ,排列呈线状或“C”形。部分细胞可观察到明显狭窄的颈部 ( 61/ 98)。IHC的表皮板一般为倾斜状 ,凹面向上 ,较厚。另外 ,IHC的表皮板通常与细胞胞体长轴成锐角或钝角。豚鼠耳蜗IHC长度为 13～ 3 1μm ,平均 ( 2 2 45± 4 14) μm ( x±s,n =98,下同 ) ;直径为 7～ 15 μm ,平均 ( 11 95±1 5 9) μm。静纤毛长度为 2～ 7 5 μm ,平均 ( 5 2 1± 1 0 0 ) μm。 结论　本研究成功建立一种能够分离到大量的、生物活性好的IHC的技术 ;内、外毛细胞单离后在形态学上的鉴别要点是表皮板 ,尤其是表皮板与细胞胞体长轴的成角特征     

小鸡基底乳头听毛细胞突触的超微结构观察

目的；进一步研究鸡的内耳毛细胞及其神经支配的形态学特征。方法：应用透射分别观察５只小鸡基底乳头的４个部位（距基底乳头远端起始部０．６ｍｍ、１．６ｍｍ，２．６ｍｍ，３．６ｍｍ）毛细胞突触的形态学特征。结果：高毛细胞（ＴＨＣ）、矮毛细胞（ＳＨＣ）与传入性和传出性神经末梢形成突触。ＴＨＣ下方与大的传入性神经末梢和小的传出性神经末梢形成突触；ＳＨＣＧ民大的传出性神经末梢和小的传入性神经末梢构成突触。结论：     

豚鼠耳蜗单离外毛细胞钙波的观察

目的：观察豚鼠耳蜗单离外毛细胞（outer hair cell,OHC)内游离钙浓度（[Ca^2]i)是否存在波动，即有无钙波。方法：健康豚鼠10只断头处死，在无Ca^2的dHanks液和含Ca^2的Hanks液中酶－机械法分离获得单离活性OHC，钙荧光抗体Fluo-3孵育后，分别加入乙酰胆碱或空白对照，用MRC－1024型激光扫描共聚焦显微镜（Bio-Rad，英国）观察OHC约50min内[Ca^2]i的变化。结果：dHanks液中加ACh组的5个OHC，[Ca^2]i呈明显的规律性的波动，即产生了钙波，钙波的周期约600s;Hanks液中加ACh组的6个OHC的[Ca^2]i均迅速升高，无钙波出现，在dHanks液和Hanks液中不加ACh分别观察了3个OHC，[Ca^2]i呈平坦型，无钙波，结论：ACh能刺激诱发豚鼠耳蜗单离OHC产生钙波。     

小鸡再生听毛细胞及其突触连接的放射自显影

目的 采用光镜放射自显影（Ｌｉｇｈｔ ｍｉｃｒｏｓｃｏｐｉｃ ａｕｔｏｒａｄｉｏｇｒａｐｈｙ,ＬＭ－ＡＲＧ）及电镜放射自显像（Ｅｌｅｃｔｒｏｎ ｍｉｃｒｏｓｃｏｐｉｃ ａｕｔｏｒａｉｏｇｒａｐｈｙ,ＥＭ－ＡＲＧ）技术,观察不鸡再生听毛细胞及其突触连接的特征。方法 ７ｄ龄纯种伊莎鸡２０只,实验组（ｎ＝１４）,连续皮下注射庆大霉素１０ｄ;对照组（ｎ＝６）。皮下注射生理盐水,用药第４ｄ开始注射氚村记胸腺     

豚鼠耳蜗单离螺旋神经节细胞外毛细胞同时分离法

随着细胞生物学及分子生物学技术的进步 ,保持活性的单离螺旋神经节细胞 ( SGC)和 (或 )外毛细胞 ( OHC)已成为听觉生理、生化、病理及药理实验的重要模型。OHC为听觉的感受细胞 ,SGC为听觉初级神经元 ,观察同一因素对 OHC及 SGC的影响有重要意义 ,这就需要同时获得来源于同一耳蜗的单离的 SGC和 OHC。为此 ,我们尝试了在同一耳蜗同时分离单离的 SGC和 OHC的可能性 ,获得较好结果 ,报告如下。1　材料与方法1 .1 　 实验动物及溶液配制选用耳廓反射阳性、体重 2 0 0～ 30 0 g的花色豚鼠 6只 ,雌雄兼有。培养液为标准细胞外液 ,组…     

听神经瘤患者离体前庭毛细胞的分离及胞内钙离子活动

目的 进一步了解离体人前庭毛细胞的胞内钙离子（Ｃａ＾２＋）活动。方法 从３例经迷路听神经瘤切除术患者中采取半规管壶腹中的前庭毛细胞，用倒置显微镜观察分离出的离体前庭毛细胞形态，用Ｃａ＾２＋敏感的荧光染料Ｆｕｒａ－２和数字影像显微镜监测细胞内Ｃａ＾２＋浓度的变化。结果 分离的前庭毛细胞主要为Ｉ型毛细胞，可在体外存活２．５ｈ。用１５０ｍｍｏｌ／Ｌ Ｋ＾＋液灌流单离的前庭毛细胞引起胞内Ｃａ＾２＋的显著升     

豚鼠耳蜗各回外毛细胞的分离

目的 :探讨豚鼠耳蜗各回外毛细胞 (OHC)的分离方法。方法 :选豚鼠 8只 ,解剖耳蜗各回组织 ,获得Corti器并采用酶消化后机械分离。结果 :各回均可获得一定数量、活性良好的 OHC,第 1、2、3、4回单离 OHC的长度依次为 2 3.81、34.5 0、6 0 .48和 71.37μm。结论 :熟悉耳蜗各回解剖、组织特性并按操作要点进行是成功分离出各回 OHC的关键。     

豚鼠耳蜗单离外毛细胞和Deiters细胞的钾离子电流及其生理功能

目的 研究豚鼠耳蜗单离外毛细胞(OHC)和Deiters细胞的钾离子电流及其特性，观察乙酰胆碱(ACh)和三磷酸腺苷(ATP)对离子电流的影响。方法 运用全细胞膜片钳技术，分别记录单离OHC和Deiters细胞的离子电流。结果 OHC的长度不同，其钾离子电流表达具有差异性，短OHC具有较大外向电流和内向电流。ACh对短OHC钾离子电流的影响较大，其作用是使0HC超极化。ATP介导的0HC内向电流是非选择性的阳离子电流。ATP介导Deiters细胞出现内向离子电流。结论 K^ 电流在OHC的电谐振中非常重要。Deiters细胞能够通过减少K^ 外流、增加K^ 内流来缓冲周围环境中K^ 浓度的变化。ACh和ATP对OHC离子电流的影响在耳蜗机制中起重要作用。     

豚鼠耳蜗单离外毛细胞外向钾电流的特性

目的：探讨豚鼠耳蜗单离外毛细胞（ＯＨＣ）钾电流（Ｉｋ）的正常值及其特性。方法：应用膜片钳全细胞记录技术及多种辅助方法,测试在不同细胞内、外液和电压刺激条件下的Ｉｋ、钾尾电流（Ｉｋｔａｉｌ）和反转电位。结果：Ｉｋ具有明显的电压依赖性和时间依赖性,在２０ｍｓ内达峰值,平均激活电压约为－３２．７ｍＶ,从激活电压至０电压时Ｉｋ增长最快,在４０ｍＶ时接近饱和。正常条件下Ｉｋ无明显“ｒｕｎ－ｄｏｗｎ现象”。细     

Salicylate-induced morphological changes of isolated inner hair cells and outer hair cells from guinea-pig cochlea

Objectives

The aim of this study is to investigate the salicylate-induced morphological changes of cochlear inner hair cells (IHCs) and outer hair cells (OHCs).

Methods

IHCs and OHCs were acutely isolated from the guinea-pig cochlea. Cells were observed under the inverted microscope and 10 mmol/L sodium salicylate solutions or 0.01 mmol/L dexamethasone-plus-salicylate solutions were applied. The cell length or the ratio between the length and width was the indices of the morphological changes in cells.

Results

Isolated IHCs did not demonstrate any significant changes in sodium salicylate solutions in 20 min and in 40 min, whereas OHCs were shortened by the 10 mmol/L sodium salicylate to 83% in 20 min and 75% in 40 min. There were no significant differences between in the dexamethasone-plus-salicylate solutions and in the control solutions after 20 min and 40 min both in IHCs and OHCs.

Conclusions

Although salicylate affected the isolated OHCs from guinea-pig cochlea, IHCs were not changed morphologically by sodium salicylate applications. Dexamethasone inhibited the salicylate-induced morphological changes of OHCs.     

Vestibular hair cells isolated from guinea pig labyrinth

Living sensory cells were isolated from the cristae ampullaris and macula utriculi of the guinea pig. Enzymatic and mechanical dissociation were used to obtain different populations of hair cells, the most predominant being type I cells. Their form varied: cell body of variable roundness, and neck and cilia of different lengths. The observation of many tilted cuticular plates supports the hypothesis of active mechanisms regulating mechanotransduction at the apex of these cells. Cell viability was verified by double fluorescent labeling (FDA-PI), which indicated that under correct conditions about 90% of the sensory cells could be maintained in vitro for several hours after dissociation. The detection of actin in the cuticular plate and cilia shows that the technique has various potential applications in morphological studies, and can contribute to investigations on the physiology of mammalian vestibular cells.     

Fast in vitro movement of outer hair cells in an external electric field: Effect of digitonin, a membrane permeabilizing agent

Isolated outer hair cells from the organ of Corti show elongation and contraction in response to an externally applied ac electric field as well as to a direct current injection into these cells. This is thought to be the basis of the positive feedback mechanism for fine tuning of the mammalian hearing organ. To test whether the mechanical response depends on the intracellular electric field or on the membrane potential, we used digitonin to shunt the membrane resistance. We observed that the application of digitonin abolished the cellular response of the outer hair cells to an ac external electric field (5–30 Hz). Coinciding with the abolition of the cellular response, the nuclear matrix started to oscillate synchronous to the external field, indicating an appreciable increase of the intracellular electric field. If the intracellular electric field was the regulating factor of the motile response, the initiation of the movement of the nuclear matrix would have been accompanied by an enhancement of the cellular movement. Our observation is therefore consistent with the interpretation that the (local) membrane potential, and not the intracellular electric field, regulates the hair cell movement.     

Differential susceptibility of avian hair cells to acoustic trauma

Five groups of 10-day-old chicks were continuously exposed to either 500 or 1500 Hz pure tone at 125 dB for 4 or 12 h and killed 10 days later. The basilar papillae were fixed, embedded in plastic, sectioned, and hair cells were counted according to type: tall or short. Short hair cells were found to be more susceptible to acoustic overstimulation than tall hair cells. Further, the position of maximum short hair cell loss varied along the length of the basilar papilla as a function of the exposure frequency while the position of tall hair cell loss did not. Similarities between morphological response of short hair cells in avians after acoustic trauma and outer hair cells in mammals are discussed.     

Inner hair cells isolation and morphological observation]

OBJECTIVE: To set up an effective technique for isolating the single inner hair cells (IHCs) and observe morphological features to distinguish IHCs from other hair cells (OHCs) in vitro. METHODS: Surface preparations contained rows of OHCs and IHCs were prepared from guinea pigs. The cluster and single IHCs were separated microsurgically combination with an enzymatic digestion. The clusters of IHCs were separated using two fine electrodes and transferred by a gentle suction using a glass micropipette. RESULTS: On the average, one guinea pig cochlear yielded approximately 30 to 50 viable solitary IHCs. The cell body of the IHCs was pear or flask shape. The nucleus was located in the central of the cell body, and the cytoplasm was filled with the structured and scattered rough granules. The stereocilia were seen in the most of IHCs (93 out of 98). The stereocilia were aligned, almost lineally or in a "C" shape, in one side on the surface of the cuticular plate. The tight neck and the angle between the cuticular plate and the axis of the cell were observed in some IHCs but not obvious in most cases, which might be due to the orientation of the cells. The length of isolated IHCs was ranged from 13 to 31 microns and with an average of (22.45 +/- 4.14) micron (mean +/- s, n = 98). The diameter of IHCs was ranged from 7 to 15 microns and with an average of (11.95 +/- 1.59) micron. The length of stereocilia was ranged from 2 to 7.5 microns and with an average of (5.21 +/- 1.00) micron. CONCLUSION: Unambiguous solitary IHCs were successfully harvested from guinea pig cochlea using a microsurgical technique. The tight neck and the angle between the cuticular plate and the axis of the IHCs have been considered as an important landmark to distinguish the IHCs from OHCs.     

Preservation of the non-rectangular cuticular plate/cell axis angle of outer hair cells

Motile properties of outer hair cells (OHCs) may contribute to sharp tuning and amplification in the mammalian cochlea. Shape changes of isolated OHCs in response to various physical and chemical influences have been investigated intensively. However, determinations of shape may have been influenced by unanticipated effects of preparation and preservation of the OHCs investigated. Thus, in a first step, lengths of freshly isolated OHCs from the guinea pig cochlea were determined using a video-enhancing magnification system. The cuticular plate/cell axis angle (CP/CA angle) was then measured in native cells and under the influence of potassium chloride and potassium gluconate incubation. To show the influence of glutaraldehyde (GA) fixation on the isolated OHCs, fixative dependent changes on cell length and CP/CA angle were recorded in native and preincubated OHCs. In these experiments, the cell length of vital isolated OHCs was between 41.5 m, in the basal turn, and 103.7 m, in the apical turn. The average CP/CA angle was 106° ± 4.2° (n = 324 cells, turns 1–4) with no statistically significant differences for the four turns. Under the influence of potassium chloride, cell length was reduced by 8.1%. Potassium gluconate incubation led to a shortening of cell length, followed by a 5.3% increase after 5 min. The CP/CA angle under potassium chloride was decreased (97.0°) and was then increased under the influence of potassium gluconate (110.7°) as a result of cuticular plate tilting. Cell shrinkage after fixation depended on the fixative's osmolarity and on the GA concentration. Increased GA levels amplified cell shrinkage from 34% for hypo-osmolar solutions to 15% in iso-osmolar and 29% in hyperosmolar solutions. The CP/CA angle of native and incubated OHCs was not different from those fixed with GA. The present data provide a rational basis for isolated OHC shape parameters. Moreover, functionally induced changes can be better interpreted when OHCs are influenced by fixatives, as shown in the GA experiments.     

小鸡基底乳头毛细胞再生中增殖细胞的免疫组织化学染色显示

利用增殖细胞核抗原（ＰＣＮＡ）免疫组织化学染色（ＳＡＢＣ法），显示庆大霉素损伤后小鸡基底乳头毛细胞再生中的增殖细胞。结果：庆大霉素组出现散在的ＰＣＮＡ阳性的增殖细胞核；正常对照组和阴性对照均为阴性。提示ＰＣＮＡＳＡＢＣ法染色是显示增殖细胞的理想方法之一。     

Two-tone suppression in cochlear hair cells

The phenomenon of two-tone suppression that is known to occur at the level of the auditory nerve is shown to also occur in the receptor potential of single presumed inner hair cells in the first turn of the guinea pig cochlea.