前庭毛细胞的反相激活模式

分布在内耳前庭各个终器的感觉毛细胞可分为两种类型,它们分别是I型毛细胞和II型毛细胞。这两种毛细胞无论是在静纤毛的长度,还是毛细胞细胞体的形状,或者神经末梢的连接方式以及与之相联系的前庭神经元都不一样。前庭毛细胞感受重力或体位改变刺激的机制是由于其插入到覆盖在其上方耳石膜或终帽内的纤毛随着这些辅助结构的惯性位移而发生弯曲,纤毛的弯曲引起毛细胞膜电位发生去极化或超极化改变,从而促使毛细胞的神经冲动信号发放增强或减弱。静纤毛朝着动纤毛的方向弯曲形成对毛细胞的兴奋性刺激,而静纤毛朝着背离动纤毛的方向弯曲则构成对毛细胞的抑制。球囊斑和椭圆囊斑都被从其中心穿越的一条狭窄的细胞带划分为两个区域,这条狭窄的细胞带被称之为微纹区,在椭圆囊斑微纹区两侧周边区毛细胞的动纤毛都排列在朝向微纹区的位置,而球囊斑微纹区两侧周边区毛细胞的动纤毛都排列在背离微纹区的位置,由此可见,每一个囊斑微纹区两侧毛细胞的极性正好完全相反。当机体沿着一个囊斑的平面从垂直于微纹区的方向产生一个加速运动时,该囊斑一侧周边区的毛细胞会因为静纤毛朝着动纤毛的方向弯曲使该侧毛细胞发生去极化而处于兴奋状态,而另一侧周边区的毛细胞却因静纤毛朝着离开动纤毛的方向弯曲使该侧毛细胞发生超极化而处于抑制状态。三个壶腹嵴上毛细胞的动纤毛都是朝着或背离椭圆囊的统一方向,其中外半规管壶腹嵴上每个毛细胞的动纤毛都是统一朝着椭圆囊,而上半规管和后半规管壶腹嵴上的每个毛细胞的动纤毛都是统一朝着半规管的方向。壶腹嵴是一个位于壶腹腔内的横位的马鞍形隆起,当其上方覆盖的胶状质终帽随着内淋巴液的流动发生相对位置移动时,壶腹嵴一侧的毛细胞纤毛必然会随着终帽顶部的偏移而发生方向一致的弯曲,从而使这半侧壶腹嵴毛细胞产生同步的去极化或超极化反应,然而壶腹嵴另外一侧毛细胞的纤毛却会因为内淋巴液在壶腹嵴上方推动终帽时在被壶腹嵴遮挡一侧的底部形成一个反方向的漩涡式回流使壶腹嵴另外一侧毛细胞的纤毛发生方向相反的弯曲,从而使壶腹嵴两侧毛细胞处于一侧兴奋而另一侧抑制的截然相反的不平衡状态。这意味着同样的加速运动方向对与之相对应的前庭终器两侧感觉上皮产生的是截然不同的刺激信号,从而造成该前庭终器两侧感觉上皮输入信号的不平衡。这种不平衡刺激模式经前庭周边神经元传入到前庭中枢神经系统,使整个从周边到中枢的前庭系统都是以这种不平衡刺激方式传递和感知机体的平衡状态。     

前庭学

970618哺乳动物前庭迷路的体外发育:周围性眩晕的研究手段/周祥宁…//天津医药一1 996,24(l)一4一7 首次在国内报告小鼠前庭迷路的体外发育。采用周祥宁和Van De Water建立的HEMA水凝胶器官培养法培养第12一13天CBA/C57小鼠胚胎的内耳原基7一8天。内耳原基的上部发育成3个半规管、椭圆囊和球囊。半规管的壶腹晴由一排感觉毛细胞和2一3排支持细胞构成。晴的上方有正在发育的峪顶。椭圆囊斑和球囊斑的表面都有一层耳石膜。这些囊斑内可见一层感觉毛细胞和1一2层支持细胞。超微结构研究发现壶腹峪、椭圆囊斑和球囊斑的毛细胞有排列规则的…     

人前庭感觉上皮扫描电镜观察

为了解人前庭器官的超微结构，借助扫描电镜技术观察了５人（１０耳）的前庭感觉上皮。结果显示：①球囊斑呈“Ｌ”形，椭圆囊斑形如打开的贝壳；②Ⅰ型感觉细胞呈烧瓶样，Ⅱ型感觉细胞呈试管状；③感觉细胞纤毛排列呈阶梯状，动纤毛最长，且位于最长的静纤毛一侧，椭圆囊斑最长的静纤毛和动纤毛靠近微纹，其极性也向微纹，球囊斑则背离微纹，水平半规管壶腹嵴的动纤毛朝向椭圆囊侧，上、后半规管壶腹嵴则朝向半规管侧；④耳石形状大小不一致，呈现两端为锥形的圆柱状晶体。     

人前庭感觉上皮扫描电镜观察

为了解人前庭器官的超微结构，借助扫描电镜技术观察了５人（１０耳）的前庭感觉上皮。结果显示：①球囊斑呈“Ｌ”形，椭圆囊斑形如打开的贝壳；②Ｉ型感觉细胞呈烧瓶样，Ⅱ型感觉细胞呈试管状；③感觉细胞纤毛排列呈阶梯状，动纤毛最长，且位于最长的静纤毛一侧，椭圆囊斑最长的静纤毛和动纤毛造近微纹，其极性也向微纹，球囊斑则背离微纹，水平半规管壶腹嵴的动纤毛朝向椭圆囊侧，上、后半规管过来腹嵴则朝向半规管侧；④耳右形状     

Smad4条件基因敲除小鼠内耳前庭的组织学变化

目的 观察Smad4条件基因敲除小鼠内耳前庭的组织学变化,探讨Smad4基因在内耳前庭发育中的作用.方法 应用冰冻切片、免疫荧光化学、激光扫描共聚焦显微镜、扫描电镜、透射电镜等技术,观察软骨组织Smad4条件基因敲除小鼠内耳前庭组织形态的变化.结果 Smad4 -/-小鼠内耳软骨囊Smad4免疫反应阴性,Smad4+/-小鼠阳性,Smad4+/+小鼠强阳性,而在前庭感觉上皮——壶腹嵴和囊斑里Smad4免疫反应均呈阳性,三个基因型间没有差别;通过扫描电镜和透射电镜以及神经丝免疫荧光染色观察,三个基因型小鼠内耳前庭均未发现病变.结论 Smad4条件基因敲除小鼠的内耳软骨囊里Smad4基因被有效剔除,但其对内耳前庭的组织结构和形态影响有限.     

CBA小鼠内耳感觉上皮的参考数据

目的测量成年CBA小鼠耳蜗和前庭的有关数据,为内耳感受器定量分析提供参考依据。方法将6只出生后3个月左右的成年CBA小鼠(12耳)的耳蜗和前庭各终器取出并制备成全耳蜗基底膜铺片和全前庭终器铺片。测量全耳蜗基底膜的总长度,以及基底膜和Corti器在耳蜗不同部位的宽度。观察并记录全耳蜗毛细胞的总数和基底膜上不同区间的毛细胞密度。观察并记录椭圆囊斑和球囊斑毛细胞的总数及其微纹区和周边区的毛细胞密度,记录壶腹嵴上的毛细胞密度。结果正常成年CBA小鼠的耳蜗基底膜长度为(5.76±0.196)毫米(平均数±标准差,下同),基底膜的宽度在耳蜗底部距起始端约1.5毫米处为(339.1±9.87)微米,在耳蜗中部距起始端约3毫米处为(304.5±11.82)微米,在耳蜗顶部距起始端约5毫米处为(300.1±7.22)微米,说明小鼠耳蜗基底膜的宽度从底回到顶回逐渐变窄。Corti器的宽度在耳蜗底部距起始端1.5毫米处为(37.80±2.24)微米,在耳蜗中部距起始端约3毫米处为(45.00±2.67)微米,在耳蜗顶部距起始端约5毫米处为(52.20±3.16)微米,可见Corti器的宽度从底回到顶回逐渐变宽。CBA小鼠全耳蜗毛细胞的总数为(3116.41±151.91)个,其中内毛细胞总数为(680.67±17.50)个,而外毛细胞的总数是(2435.8±143.46)个。耳蜗内、外毛细胞的平均密度为(541.1±9.36)个/毫米,其中内毛细胞的平均密度为(118.3±2.68)个/毫米,外毛细胞的平均密度为(422.8±11.87)个/毫米,耳蜗毛细胞在耳蜗基底膜上不同区间的毛细胞密度无明显差异(P>0.05)。小鼠椭圆囊斑上的毛细胞总数为(3300±177.51)个,球囊斑上的毛细胞总数为(3045±361.57)个。前庭球囊斑和椭圆囊斑微纹区和周边区的毛细胞密度基本相同(P>0.05),两个囊斑微纹区的平均毛细胞密度为(40.2±6.59)个/0.0025mm2,两个囊斑周边区的平均毛细胞密度为(53.2±7.18)个/0.0025mm2,可见囊斑微纹区的毛细胞密度低于周边区。尽管小鼠上半规管和后半规管壶腹嵴的毛细胞区被位于嵴中央的上皮细胞分隔为两个区域,但三个壶腹嵴上的毛细胞密度基本相同,其平均密度为(44.7±7.15)个/0.0025mm2。结论本实验所得CBA小鼠耳蜗和前庭测量数据,为进一步定量观察CBA小鼠内耳病理学改变提供了重要的参考依据。     

Carboplatin对灰鼠前庭系统的影响

本研究目的在于调查一种抗肿瘤药Carboplatin（100m／kg）对灰鼠前庭器官功能与形态的影响。注射Carboplatin后，冷水诱发眼震持续时间明显缩短。急性形态学损害主要发生在Ⅰ型毛细胞的传入神经末梢和胞核。另外，壶腹嵴的形态学损害比球囊斑和椭园囊斑发生早而且更为严重。在囊斑内，微纹区是病变的主要部位。用药后30天，壶腹嵴和囊斑有较多Ⅰ型毛细胞缺失，然而Ⅱ型毛细胞未受明显影响。上述结果表明Carboplatin具有迅速的强烈的前庭毒性作用，Ⅰ型毛细胞和传入神经末梢是主要受损部位。     

Smad4 基因缺陷小鼠耳形态学改变的初步研究

目的研究Smad4基因缺陷小鼠中耳及内耳的病理形态学改变，探讨Smad4基因对中耳及内耳发育的影响。方法利用建立的Smad4基因敲除嵌合体小鼠模型，通过火棉胶包埋HE染色观察Smad4（＋/＋）与Smad4（＋／-）小鼠的情况；通过耳蜗基底膜铺片琥珀酸脱氢酶染色观察Smad4（＋／＋）与Smad4（＋／-）小鼠的耳蜗内、外毛细胞数量；应用扫描电镜观察Smad4（＋／＋）与Smad4（＋／-）小鼠的内耳超微结构。结果火棉胶包埋HE染色显示：Smad4（＋／＋）与Smad4（＋／-）小鼠耳蜗大小、耳蜗转数均未见异常，中耳鼓膜正常，听小骨锤骨、砧骨、镫骨及关节结构正常，骨细胞排列紧密，Smad4（＋／＋）与Smad4（＋／-）之间没有差异。Smad4（＋／＋）小鼠耳蜗Corti器结构完整，未圯异常，血管纹厚薄均匀，血管腔腔径大小均匀。内、外毛细胞及内外柱细胞、支持细胞无异常，螺旋神经节细胞未见缺失；Smad4（＋／-）小鼠耳蜗钩端至-回外毛细胞轮廓不清，呈均质化，细胞核消失。Deiter细胞核下沉或消失，相应的螺旋神经节细胞大量缺失。耳蜗基底膜铺片琥珀酸脱氢酶染色显示：Smad4（＋／-）和Smad4（＋／＋）小鼠均有明显的局限于Corti’S器底同的外毛细胞缺失，其中Smad4（＋／-）小鼠外毛细胞的缺失，比Smad4（＋／＋）小鼠更明显（P〈0．01），两个基因型小鼠的内毛细胞均未见缺失。扫描电镜显示：Smad4（＋／＋）小鼠未见明显病理变化，Smad4（＋／-）小鼠耳蜗钩端外毛细胞静纤毛广泛散在性缺失，外毛细胞的表皮板穿孔、自溶，其周边与指状突小皮板断离。两个基因型小鼠耳蜗内毛细胞纤毛均未见明显改变。结论Smad4基因敲除后内耳形态发生明显改变，表明Smad4基因缺陷导致小鼠内耳细胞损害。     

小鼠前庭器官的形态发生

目的了解小鼠前庭器官发育的形态学特征及演变规律.方法利用光镜、扫描电镜、透射电镜观察C57BL/6小鼠从胚胎第8天到刚出生期间前庭器官发育过程中的形态变化.结果 C57BL/6小鼠的前庭器官在胚胎第10.5天开始发育,胚胎第11.5天形成上、后半规管始基,到胚胎第12天水平半规管始基才逐渐形成,椭圆囊已出现许多原始的感觉纤毛,而到胚胎第13天,球囊才开始发育;到胚胎第15天,椭圆囊、球囊、壶腹嵴初具成熟形态,毛细胞和支持细胞也初具雏形,到出生时,前庭器官已基本发育成熟.结论 C57BL/6小鼠前庭感觉细胞在胚胎第12天开始分化,感觉上皮的形态从胚胎第12天至第18天变化最明显.椭圆囊、壶腹嵴的发生较早,随后才形成球囊,到出生时前庭感觉器官已基本发育成熟.     

前庭器官超微结构研究及结构图构建

目的通过扫描电镜观察小鼠椭圆囊、球囊、壶腹超微结构,研究分析并据此构建前庭器官新的结构示意图。方法选取3个年龄段小白鼠各10只,分别是年轻组≤2个月、中年组2~12个月、老龄组>12个月。分离出椭圆囊、球囊、壶腹,采用扫描电镜技术样品制备方法制备样品,应用扫描电镜进行样品观察。结果扫描电镜下可以得到:①椭圆囊斑及球囊斑不同层面图片:表面为堆积并相互黏附的"表面耳石",表面耳石下是无结构胶状质;底层表面耳石深入到无结构胶质层里;无结构胶质层下面是毛细胞纤毛及"纤毛间耳石"层,不同纤毛束之间均有纤毛间耳石存在,立于支持细胞表面,表面平坦;蜂窝状胶质物质联接无结构胶质层、纤毛间耳石及毛细胞纤毛。②壶腹超微结构的图片:嵴帽是无结构的胶状质与壶腹外侧壁紧贴,但较易分离,嵴帽和壶腹外侧壁之间有纤细的晶状体物质,在壶腹嵴两侧壁上也有纤细晶体物质(壶腹嵴表面耳石);不同的毛细胞纤毛之间有耳石结构的存在(壶腹嵴纤毛间耳石)。结论通过对前庭器官扫描电镜的观察,发现了椭圆、球囊斑及壶腹的新结构成分,由此构建出新的前庭器官超微结构示意图。     

Quantitative immunoelectron microscopic localization of Na, K-ATPase alpha-subunit in the epithelial cells of rat vestibular apparatus.

Na, K-ATPase was quantitatively localized in the epithelial cells of rat vestibular apparatus such as macula utriculi, macula sacculi and crista ampullaris. Immunogold localization method was carried out at the saturation level of antibody using an affinity purified antibody against the alpha-subunit of rat kidney Na, K-ATPase. Numerous gold particles were found on the basolateral membrane of the dark cells, a small number of gold particles were found on the basolateral membrane of the transitional epithelium cells and hair cells, but the luminal surface membranes of the hair cells, transitional epithelium cells, planum semilunatum cells and dark cells were rarely labeled by gold particles. Significance of the abundant localization of Na, K-ATPase on the basolateral surface of the dark cells in the production of endolymph was discussed.     

Isolation of and calcium mobilization in vestibular hair cells of the guinea pig

Vestibular hair cells were isolated from the macula utriculi, macula sacculi and crista ampullaris of the guinea pig, using enzymatic and mechanical techniques. The cells could be classified into two types: flask-shaped ones with a neck and rod- or round-shaped ones without a neck. The flask-shaped cells were thought to be type I cells, the rod-shaped cells type II cells, while the round-shaped cells could have been type I or type II cells. The intracellular free calcium ion concentrations [( Ca2+]i) of these cells were determined using the Ca2(+)-sensitive dye Fura-2 and digital imaging miroscopy. In the resting state, [Ca2+]i in the nucleus and cuticular plate was variable in both types of cells. The 150 mM KCl stimulation, which might induce a depolarization, resulted in a temporary increase in [Ca2+]i in both types of cells. In the presence of 1 micron ionomycin, there was an irreversible increase in [Ca2+]i in both types of cells. These observations aid in elucidating vestibular function.     

Peripherin immunoreactivity labels small diameter vestibular 'bouton' afferents in rodents.

Recent morphophysiological studies have described three different subpopulations of vestibular afferents. The purpose of this study was to determine whether peripherin, a 56-kDa type III intermediate filament protein present in small sensory neurons in dorsal root ganglion and spiral ganglion cells, would also label thin vestibular afferents. Peripherin immunohistochemistry was done on vestibular sensory organs (cristae ampullares, utriculi and sacculi) of chinchillas, rats, and mice. In these sensory organs, immunoreactivity was confined to the extrastriolar region of the utriculus and the peripheral region of the crista. The labelled terminals were all boutons, except for an occasional calyx. In vestibular ganglia, immunoreactivity was restricted to small vestibular ganglion cells with thin axons. The immunoreactive central axons of vestibular ganglion cells form narrow bundles as they pass through the caudal spinal trigeminal tract. As they exit this tract, several bundles coalesce to form a single, narrow bundle passing caudally through the ventral part of the lateral vestibular nucleus. Finally, we conclude that all labelled axons and terminals were vestibular afferents rather than efferents, as no immunoreactivity in the vestibular efferent nucleus of the brainstem was observed.     

质膜钙ATP酶异构体1～4的剪接体在新生大鼠前庭器官的表达

目的：研究质膜钙 ATP 酶异构体（plasma membrane Ca2＋－ATPase isoforms,PMCAs）1～4（PM-CA1～4）的 A 端和 C 端剪接变异体在新生大鼠前庭器官的表达。方法取出生2天的健康 SD 大鼠10只,断头后分离出前庭器官（椭圆囊斑和球囊斑）,提取总 RNA,通过逆转录聚合酶链反应（RT－PCR）方法,检测 PMCA1～4的 A 端和 C 端剪接变异体的表达。结果在新生大鼠的椭圆囊斑和球囊斑 PMCA1～4表达的剪接体分别为PMCA1x／b,PMCA2w／（a、b）,PMCA3z／（a、b、c）和 PMCA4（x、z）／b。结论在新生大鼠前庭器官,PMCA1、PM-CA2、PMCA3和 PMCA4之间表达的 A 端和 C 端剪接变异体类型均不同,这可能是由于椭圆囊斑和球囊斑对这些 PMCA 亚型有着不同的 Ca2＋调节需求。     

BMP4/Smad4在C57BL/6小鼠内耳前庭发育不同阶段的表达

目的探讨骨形态形成蛋白4(bone morphogenetic protein 4,BMP4)和Smad4蛋白(drosophila mothers against decapentaplegic protein 4)在C57BL/6小鼠内耳前庭发育不同阶段的表达。方法选择从胚胎第10天(E10)到胚胎第20天(E20)每天的孕鼠各两只(共22只),取E10～E17的胚胎头、E18～E20的胚胎内耳,通过冰冻连续切片、免疫组化或免疫荧光染色,观察小鼠胚胎内耳前庭发育过程中BMP4/Smad4的表达情况。结果 BMP4从E10开始,在间充质浓聚前就有表达;间充质一开始浓聚,BMP4在其中就有较丰富的表达;早期主要表达在前庭囊及前庭囊周围的间充质,在胚胎发育的后期,其在软骨囊及前庭上皮里有广泛阳性表达;Smad4在小鼠内耳前庭的表达情况与BMP4不一致,E10到E12的小鼠内耳Smad4表达阴性,E15时各个壶腹嵴、囊斑里才有较明显的Smad4表达,而内耳周围软骨囊到E16时才有明显的Smad4表达。结论 BMP4与小鼠内耳前庭形态形成及毛细胞分化发育、功能形成有关;Smad4与BMP4的表达时空特征不同,Smad4可能主要参与了小鼠内耳前庭发育后期的形态塑形和功能发育。     

Morphological changes induced by administration of a Na+,K+-ATPase inhibitor in normal and hydropic inner ears of the guinea pig

The objective of this study was to determine the effects of ouabain, a Na+,K+-ATPase inhibitor, in inner ears. Administering ouabain locally through the round window and vestibule, resulted in degenerative changes in cochlear and vestibular sensory cells and limbal fibrocytes, but the stria vascularis and spiral ligament were less affected. The position of Reissner's membrane was rarely changed. Vacuolar spaces in the sensory epithelia of cristae, maccula utriculi and macula sacculi increased in number. Nystagmus was a common occurrence with or without demonstrating degeneration of vestibular sensory cells. By administering ouabain systemically, the course of developing endolymphatic hydrops could not be altered in the ears with endolymphatic duct blockage. Edema of nerve endings of inner hair cells and vestibular sensory cells was frequently observed with administration of a high concentration of ouabain in both normal and hydropic ears, but edema was reversible. Degeneration of some vestibular sensory cells were observed in hydropic ears with a long survival time. The mechanism of selective sensitivity or non-sensitivity of inner ear tissues to ouabain is discussed.     

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.     

An approach for precise three-dimensional modeling of the human inner ear

For further morphological and physiological research, it is vital to establish precise three-dimensional models of the whole inner ear including the details of the membranous components. With the system of a projector and a high-resolution digital camera, 2 complete serial unstained celloidin sections of fresh human temporal bones were digitized as high-resolution images which were then sorted, calibrated, aligned and segmented using the 3D-Doctor software. Finally, 2 precise three-dimensional models of the inner ear were generated by simple surface rendering. The contours of tiny structures such as the crista ampullaris, the macula utriculi and the macula sacculi could be observed clearly. Our study suggests that it is technically feasible to employ complete serial unstained celloidin sections for precise three-dimensional reconstruction and that this helps reduce errors and laboratory workload. Moreover, the use of a high-resolution digital camera and the autoalignment function of 3D-Doctor further increase the accuracy of the models.     

Type II collagen distribution in the ear of the developing chick embryo

The localization of type II collagen was immunohistochemically studied in the developing chick ear using monoclonal antibodies. Type II collagen appeared under the basal lamina of the otocyst from developmental stages 14 to 16. In the otic capsule, endolymphatic duct, and semicircular canal membrane, type II collagen appeared in stage 23 or 24. From stages 28 to 29, type II collagen appeared in the primitive columella, endolymphatic sac, and fibrocartilaginous plate. Type II collagen was first observed in the crista ampullaris, basilar membrane, macula sacculi, and utriculi in stages 30 and 31. Type II collagen was not detected in the endolymphatic sac beyond developmental stage 37 and the amount of type II collagen in the otic capsule and columella decreased after stage 40. The wide distribution of type II collagen in the inner ear throughout the development of the chick embryo suggests that this collagen may act as a basic structural component of the ear.