中脑导水管周围灰质支配桥脑Barrington‘s核内骶髓投射神经元的 …

本文研究采用电镜双标记技术对大鼠中脑导水管周围灰神经元投射到桥脑Ｂａｒｒｉｎｇｔｏｎ’ｓ核的轴突与该核内投射到骶髓的神经元的胞体和树突触关系进行了探讨。将生物素标记的葡聚糖胺（ＢＤＡ）注射于中脑导水管周围灰用来标记它发出的轴突终末，将辣根过氧化物酶（ＨＲＰ）注射于脊髓的骶髓部分，用来标记Ｂａｒｒｉｎｇｔｏｎ’ｓ核内投射至骶髓的神经元。显色后透射电镜观察发现，ＢＤＡ标记的轴突终末与ＨＲＰ标记的胞体和     

家兔延髓巨细胞网状核内突触小球的超微结构的研究

有关延髓巨细胞网状核内突触小球的超微结构,迄今尚未见专文报道,为此,用健康成兔6只,经颈总动脉以生理盐水灌流冲洗,快速断头,迅速取下平闩以上水平的延髓(厚2mm),经5％戊二醛磷酸缓冲液作整体固定,解剖镜下取出延髓巨细胞网状核组织块,复经5％戊二醛及1％锇酸双固定,常规脱水,环氧树脂618包埋,LKB超薄切片机切片,厚约500A。醋酸铀和枸椽酸铅双染。H—600电镜下观察,结果如下: 家兔延髓巨细胞网状核内有大量轴突终末及树突。轴突终末的形状及大小很不一致,其内含有密集的突触小泡及线粒体,多数为突触前成分。树突干或树突棘有Ⅰ、Ⅱ两型。Ⅰ型不含突触小泡,Ⅱ型含少量突触小泡。轴突与树突间形成复杂的突触联系。     

大鼠内侧视前区支配Barrington氏核内骶髓投射神经元的光电镜研究

下丘脑内侧视前区 ( Medial preoptic area,MPO)在神经内分泌和生殖活动中起重要作用 [1,2 ]。Barrington氏核是一个与排尿反射有密切关系的核团 ,又称为脑桥排尿反射中枢。众所周知 ,性行为 (如射精 )与排尿活动密切相关 ,性活动时常伴随排尿的抑制。近来的研究表明 MPO神经元发出的轴突投射至 Barrington氏核[3,4 ] 。但这些投射纤维是否与 Barrington氏核内投射至骶髓神经元形成直接突触的联系尚缺乏证据。因此 ,本研究在光镜及电镜水平采用双标技术对上述问题进行了探讨。材料和方法　实验用体重为 2 0 0～ 2 5 0 g的成年雄性 SD大…     

脑室内注射链脲佐菌素大鼠海马神经元和突触的超微结构异常

目的:观察侧脑室内重复注射小剂量链脲佐菌素(streptozocin,STZ)阿尔茨海默氏病(alzheimer disease,AD)模型大鼠的学习记忆和海马神经元的超微结构改变.方法:采用Morris水迷宫进行行为学测试;取海马CA1区组织制成超薄切片,透射电镜观察.结果:模型组大鼠Morris水迷宫平均游泳时间及平均游泳距离明显延长.海马CA1区神经元出现程度不等的退行性变.细胞核形态不规则.部分核内染色质浓集;胞浆内脂褐素颗粒增多,高尔基囊泡扩张.严重者出现早期细胞凋亡改变.神经毡内可见有髓鞘轴突胞质内脂褐素颗粒明显增多,突触结构异常,突触小泡聚集增多,分布无序.突触后膜胞质面上的致密斑不规则增厚,或断断续续不完整.结论:侧脑室内注射STZ可引起大鼠海马神经元和突触的超微结构病变,导致大鼠学习记忆能力减退.     

血管性痴呆小鼠海马神经元超微病理特征研究

目的：探讨血管性痴呆(VD)小鼠海马神经元超微病理特征及其变化的意义。方法：采用双侧颈总动脉线结、反复缺血—再灌注法,制作小鼠VD动物模型。取两组小鼠海马组织制成超薄切片,透射电镜观察。结果：(1)假手术组：海马神经元和神经毡结构均正常。(2)VD模型组：海马神经元核肿胀、有局部凹陷现象;核周体细胞器明显减少,多聚核糖体稀散;仅残留受到破坏的高尔基体和粗面内质网、线粒体变性。髓鞘层裂;轴突中神经微管结构模糊。神经毡中可见树突和轴突不同程度水肿,尤其是树突呈现极度扩张形成不规则的“气球”,其中含有许多大小不等的薄膜空泡。突触数量显著减少,可见穿孔和异形的突触;有的突触小泡破裂,呈片状均质化。结论：海马神经元的超微结构病变导致神经元功能异常、突触可塑性降低,可能在VD的病因中起重要作用。     

人胚胎小肠肌间神经丛超微结构观察

有关人胚胎小肠肌间神经丛组织发生超微结构的研究,国内外尚未见报道。本文用透射电镜观察了28例(8—28周)人胚胎空肠肌间神经丛的组织发生,现将结果报道如下:眙儿第10周的空肠内即可见明显的肌问神经丛。神经节稀少,断面多呈椭圆形,神经细胞和神经胶质细胞位于神经节的周边。神经节的中部或一端为大量并列走行的无髓神经纤维。神经节的周围,内由一薄层膜样神经胶质细胞突起包绕,外由数层幼稚的扁平状成纤维细胞包被,节内神经元咆体较大,形态不规则,细胞质较丰富,细胞器少,只有多量的核糖体与少量线粒体。胞核大而圆,位于细胞中央,异染色质少,着色淡,核仁明显,神经胶质细咆相对较多,胞质少,其内有一定量的粗面内质网,游离核糖体和线粒体等。胞核较小,着色深,形态     

中枢神经细胞瘤的超微结构观察

应用光镜检查及免疫标记,对2例中枢神经细胞瘤进行电镜观察.结果显示,中枢神经细胞瘤在电镜下具有一定的结构特征：瘤细胞间可查见桥粒样结构;胞质内有神经分泌颗粒和哑铃状致密核心颗粒;胞突内有丰富的微管和囊泡状结构.在外科病理诊断中,中枢神经细胞瘤难以与少突胶质细胞瘤、透明细胞室管膜瘤等肿瘤鉴别.电镜检查对鉴别诊断有比较重要的意义.肿瘤细胞胞突内的微管和囊泡、胞质内的神经内分泌颗粒等超微结构与免疫组织化学标记一致,同时也提示肿瘤起源于神经元细胞.     

三叉神经初级传入纤维终末的超微结构特点及突触联系

本文用注射纯酒精的方法成功地毁损了三叉神经根 ,获得了理想的溃变效果 ,电镜下对溃变的三叉神经初级传入纤维终末的超微结构形态及其突触联系进行了系统研究。材料与方法 :选用ＳＤ大鼠 2 2只 ,体重 1 80～ 2 5 0ｇ .腹腔内注射戊巴比妥 (35ｍｇ ｋｇ)麻醉 ,于颅顶上方正中矢状位正中线的中后 1 3旁开 2ｍｍ处用电钻打一直径约 1ｍｍ的小孔 ,用 1 5 μｌ微量注射器向三叉神经根的方向缓慢注入纯酒精 1 5 μｌ,术后分别存活 1～ 4天 ,存活时间一到 ,向大鼠腹腔内注入戊巴比妥麻醉 ,经升主动脉灌入生理盐水 6 0ｍｌ,继灌入用磷酸缓冲液 (…     

败血症中白鲢重要器官超微结构的观察

近几年来,白鲢出血性败血症已在全国范围内蔓延,对淡水养殖业危害极大。本文对患此症的白鲢的八种重要器官之超微结构进行了电镜观察,结果是:1.脾脏:白髓与红髓已无法区分,脾脏内充满红细胞。网状细胞肿胀,质膜多处破损,胞核变小,核膜破裂,染色质边集,核质稀薄。咆浆内有大量残留体与空泡(图1×5700).2.肌肉:病变明显,以水肿和出血为主。部分肌原纤维断裂,肌丝溶解消失(圈2×3400)。3.肝脏:病变多为胞核缩小,核膜增厚。糖原颗粒减少。线粒体肿胀空泡化。溶酶体、残体与脂滴明显增加(图3×2300)。4.心脏:     

呼肠病毒与细胞凋亡

从SARS患者生前咽拭子和尸检肺组织分离病毒阳性的培养细胞超薄切片中,在电子显微镜下不仅发现了呼肠病毒,而且还查见具有超微结构形态特征的凋亡细胞。凋亡早期的感染细胞,其细胞核染色质浓缩、边集显著,胞浆内尚可查见病毒包涵体的残迹。多数凋亡细胞胞浆内未查见呼肠病毒及其包涵体。在早期,凋亡细胞胞核形状变化不大,核染色质呈不规则的边集、浓缩,或呈平台状。继而,凋亡细胞胞核形状高度不规则,染色质浓缩、致密,可见核孔残迹,但细胞轮廓尚保存完好,外周可查见含核质凋亡小体。到后期,凋亡细胞高度皱缩．核固缩并碎裂成细小的片块或颗粒,胞质稀少,胞体呈芽球状,细胞膜外围可查见大小不等、形状多样的含核质凋亡小体。此研究结果提示：与SARS相关呼肠病毒所诱导的细胞凋亡有可能在SARS的发病机制中起重要作用。     

Electron microscopic studies of medullary synaptic inputs to vasopressin-containing neurons in the hypothalamic paraventricular nucleus

We have observed the ascending projections from the lower brain stem to the magnocellular vasopressin-like immunoreactive (VP-LI) neurosecretory neurons in the paraventricular nucleus (PVN) using electron microscopy. The tissues were prepared by a double labeling technique combining anterograde tracing after iontophoretic injection of wheat germ agglutinin-coupled horseradish peroxidase (WGA-HRP) in the A1 group (lateral reticular nucleus in the medulla oblongata) with VP immunocytochemistry. Both the WGA-HRP-labeled and the unlabeled axon terminals made synaptic contacts with VP-LI cell bodies and processes in the PVN. This indicates a direct synaptic influence of medullary A1 group on the secretory activity of the VP-containing neurons in the hypothalamic paraventricular nucleus.     

Nanofibrous Patches for Spinal Cord Regeneration

The difficulty in spinal cord regeneration is related to the inhibitory factors for axon growth and the lack of appropriate axon guidance in the lesion region. Here scaffolds are developed with aligned nanofibers for nerve guidance and drug delivery in the spinal cord. Blended polymers including poly(L ‐lactic acid) (PLLA) and poly(lactide‐co‐glycolide) (PLGA) are used to electrospin nanofibrous scaffolds with a two‐layer structure: aligned nanofibers in the inner layer and random nanofibers in the outer layer. Rolipram, a small molecule that can enhance cAMP (cyclic adenosine monophosphate) activity in neurons and suppress inflammatory responses, is immobilized onto nanofibers. To test the therapeutic effects of nanofibrous scaffolds, the nanofibrous scaffolds loaded with rolipram are used to bridge the hemisection lesion in 8‐week old athymic rats. The scaffolds with rolipram increase axon growth through the scaffolds and in the lesion, promote angiogenesis through the scaffold, and decrease the population of astrocytes and chondroitin sulfate proteoglycans in the lesion. Locomotor scale rating analysis shows that the scaffolds with rolipram significantly improved hindlimb function after 3 weeks. This study demonstrates that nanofibrous scaffolds offer a valuable platform for drug delivery for spinal cord regeneration.     

激光照射对急性脊髓损伤后脊髓再生的促进作用

建立大鼠皮质脊髓背侧束全横断模型,利用弱激光照射脊髓受损部位的皮肤,观察激光照射对急性脊髓损伤后脊髓再生的促进作用.30只SD大鼠,随机分成对照组和照射组.照射组:急性皮质脊髓背侧束全横断后15 min进行连续14 d采用弱激光照射脊髓受损部位的皮肤.对照组:急性皮质脊髓背侧束全横断后未行弱激光经皮照射治疗.术后两组分别于第3,7,14 d分别取材,用苏木精-伊红染色法(HE)染色和免疫荧光标记染色观察.实验发现,脊髓损伤后14 d,照射组的空洞及瘢痕形成面积小于对照组,有统计学差异(p<0.05);对照神经胶质酸性组蛋白(GFAP)和硫酸软骨素(CS)表达强烈分布紧密,照射组GFAP和CS56表达达微弱且分布稀疏;对照组少量神经微丝蛋白(NF)在损伤区周围,神经生长相关蛋白(GAP43)形态肿大变形分布紊乱,照射组大量成纤维丝状的NF分布在损伤区周围,并与GAP43相伴行.结果表明,脊髓损伤急性期采用弱激光照射脊髓受损部位的皮肤,可减少脊髓损伤后空洞形成,并促进轴突再生.     

Training Neural Stem Cells on Functional Collagen Scaffolds for Severe Spinal Cord Injury Repair

Neural stem cells (NSCs) transplantation is regarded as a promising therapeutic strategy to treat severe spinal cord injury (SCI) by compensating the neuronal loss. However, significant challenges including long‐term survival, directed neuronal differentiation, and functional integration of the transplanted NSCs and their progenies within the host spinal cord are yet to be solved. In this study, NSCs are trained on differently modified collagen scaffolds to increase their neuronal differentiation rate when cultured under the simulated SCI microenvironment. Then, a functional scaffold is screened out, on which the cultured NSCs show high neuronal differentiation rate and generate both sensory and motor mature neurons. Subsequently, that NSC seeded functional scaffold is transplanted into a rat severe SCI model. The results show that higher endogenous neurogenesis efficiency as well as in vivo survival and neuronal differentiation rate of the grafted NSCs are observed. Moreover, both sensory and motor neurons are found to be differentiated from the grafted NSCs in the lesion site and those newly generated neurons can functionally interact with each other and the host neurons. Taken together, the in vitro training systems for modulating the differentiation profiles of NSCs are instructive and exhibit strong potentials for SCI treatments.     

Peripheral Nerve‐Derived Matrix Hydrogel Promotes Remyelination and Inhibits Synapse Formation

Regeneration of injured nerve tissues requires intricate interplay of complex processes like axon elongation, remyelination, and synaptic formation in a tissue‐specific manner. A decellularized nerve matrix‐gel (DNM‐G) and a decellularized spinal cord matrix‐gel (DSCM‐G) are prepared from porcine sciatic nerves and spinal cord tissue, respectively, to recapitulate the microenvironment cues unique to the native tissue functions. Using an in vitro dorsal root ganglion–Schwann cells coculture model and proteomics analysis, it is confirmed that DNM‐G promotes far stronger remyelination activity and reduces synapse formation of the regenerating axons in contrast to DSCM‐G, Matrigel, and collagen I, consistent with its tissue‐specific function. Bioinformatics analysis indicates that the lack of neurotrophic factors and presence of some axon inhibitory molecules may contribute to moderate axonal elongation activity, while laminin β2, Laminin γ1, collagens, and fibronectin in DNM‐G promote remyelination. These results confirm that DNM‐G is a promising matrix material for peripheral nerve repair. This study provides more insights into tissue‐specific extracellular matrix components correlating to biological functions supporting functional regeneration.     

实验性免疫介导的运动神经元损伤中神经丝异常的超微结构观察

为了观察免疫介导的神经元损伤过程中脊髓前角运动神经元超微结构的病变特征，将新鲜的猪脊髓前角匀浆加佐剂注入Lewis大鼠的背部皮下，每月一次，连续四个月。在最后一次免疫后2个月，灌注固定取材。制作超薄切片，应用光镜及透射电镜观察脊髓前角运动神经元及其突起的形态学改变。结果发现脊髓前角运动神经元有不同程度的变性、丢失。残存神经元的核周体内有排列紊乱的神经丝异常聚集，构成有界膜包绕的球形或类圆形包涵体，其突起内还有大量线粒体和溶酶体聚集。其次，尚可见线粒体变性及高尔基复合体扁囊和粗面内质网池的扩张。因此认为，在免疫介导的神经元损伤过程中，神经丝的异常聚集可能与神经元的变性、丢失有关。     

猪脊髓前角匀浆免疫后豚鼠脊髓前角运动神经元的超微病理特征

应用透射电子显微镜观察猪脊髓前角匀浆免疫后豚鼠脊髓前角运动神经元的超微结构改变,并进一步探讨其发病机制。结果显示：免疫后豚鼠脊髓前角运动神经元可见内质网扩张、线粒体肿胀;胞浆基质及细胞器致密化;有髓神经纤维内神经丝局部积聚、大量线粒体及溶酶体聚集;前根及坐骨神经大的有髓神经纤维轴索萎缩,髓鞘结构保存相对较好。以上结果提示自身免疫机制能诱导脊髓前角运动神经元的损伤,轴浆转运异常可能参与其致病过程。     

免疫介导豚鼠脊髓运动神经元损伤的超微结构及钙稳衡改变

应用常规透射电镜及草酸盐-焦亚锑酸盐技术原位固定细胞内钙,对豚鼠脊髓前角细胞内的钙分布进行超微定位,探讨钙稳衡改变在免疫介导运动神经元损伤中的作用.结果发现模型组豚鼠脊髓前角运动神经元可见粗面内质网扩张、线粒体肿胀、嵴排列紊乱等.神经元周围胶质细胞增生.在运动神经元扩张的粗面内质网池和线粒体内室可见数量不等颗粒状电子致密的钙沉积物.线粒体内室内钙沉积颗粒与线粒体肿胀的程度相关.星形胶质细胞内肿胀的线粒体内室及扩张的粗面内质网池内也可见电子致密钙沉积颗粒.因此认为,钙稳衡失调参与了免疫介导的运动神经元损伤过程.     

In vivo validation of custom-designed silicon-based microelectrode arrays for long-term neural recording and stimulation

We developed and validated silicon-based neural probes for neural stimulating and recording in long-term implantation in the brain. The probes combine the deep reactive ion etching process and mechanical shaping of their tip region, yielding a mechanically sturdy shank with a sharpened tip to reduce insertion force into the brain and spinal cord, particularly, with multiple shanks in the same array. The arrays' insertion forces have been quantified in vitro. Five consecutive chronically-implanted devices were fully functional from 3 to 18 months. The microelectrode sites were electroplated with iridium oxide, and the charge injection capacity measurements were performed both in vitro and after implantation in the adult feline brain. The functionality of the chronic array was validated by stimulating in the cochlear nucleus and recording the evoked neuronal activity in the central nucleus of the inferior colliculus. The arrays' recording quality has also been quantified in vivo with neuronal spike activity recorded up to 566 days after implantation. Histopathology evaluation of neurons and astrocytes using immunohistochemical stains indicated minimal alterations of tissue architecture after chronic implantation.     

Messenger RNA localization and further characterisation of the putative tachykinin receptor NK4 (NK3B).

We have previously shown that a cloned receptor, highly homologous to the NK3 tachykinin peptide receptor, encodes a novel functional tachykinin receptor NK4. Examining sites of receptor mRNA expression by Northern blot we show that NK4 mRNA is expressed in numerous rat tissues, in contrast to the NK3 receptor which has been shown to have a distribution principally in nervous tissues. We have localised the NK4 receptor mRNA in rat brain and spinal cord using in situ hybridisation. NK4 receptor mRNA is widely expressed in neurons in the rat central nervous system, including cerebral cortex, hippocampus, hypothalamus and dorsal horn of the spinal cord. During peripheral inflammation of the hindpaw, NK4 mRNA shows complex patterns of regulation. We have also investigated some pharmacological properties of this receptor expressed ectopically in Xenopus oocytes. We show that the functional antagonism of dynorphin at the NK4 receptor is reversed by the non-specific opioid antagonist naloxone and that tachykinin-evoked responses at the NK4 receptor are inhibited by the non-peptide NK3 receptor antagonist SR142801 in a concentration dependent manner.