Nogo—p4与NgR结合抑制神经干细胞分化为双极形星形胶质细胞的突起生长

目的观察Nogo—p4是否通过与NgR结合的途径对大鼠脊髓来源神经干细胞分化形成双极形星形胶质细胞突起长度产生抑制。方法取4只出生24h内的Wistar大鼠,悬浮培养法培养大鼠脊髓来源的神经干细胞。把神经干细胞分为A、B、C、D四组,A组加入血清,B组加入血清和Nogo—p4,C组神经干细胞经RNA干扰沉默NgR基因后加入血清分化,D组神经干细胞经RNA干扰沉默NgR基因后加入血清和Nogo—p4。分化第7d,GFAP抗体标记星形胶质细胞,使用Image—ProPlus5．0软件测量双极形星形胶质细胞突起长度。结果神经干细胞分化第7d,四组均可形成双极形星形胶质细胞。B组中双极形星形胶质细胞的突起长度明显短于其它各组。A、C、D组中双极形星形胶质细胞的突起长度没有显著差异。结论Nogo—p4经与NgR结合途径显著抑制脊髓来源神经干细胞分化成的双极形星形胶质细胞的突起生长。     

“癫痫”线虫解析突触维持新机制

正突触是神经元与其靶细胞之间形成的执行信号传递功能的特化结构,由信号输出的突触前膜(通常位于轴突)和信号输入的突触后膜(通常位于树突)组成.高等动物的突触浸润于复杂的微环境当中并受其影响.例如,在中枢神经系统中,神经胶质细胞,尤其是星形胶质细胞和小胶质细胞,可通过释放多种因子以及直接的细胞-细胞接触,来调控突触的形成和功能.低等生物秀丽隐杆线虫(Caenorhabditis elegans)虽然没有发达的神经胶质细胞体系,但其神     

神经肌肉接头突触发育信号机制研究进展

神经肌肉接头是目前研究较为深入的一种经典外周胆碱能化学突触。神经肌肉接头突触形成依赖于运动神经元与骨骼肌细胞之间的精细相互作用和复杂信号传递。此外,胶质细胞在神经肌肉接头突触发育和成熟过程中亦发挥重要功能。现将主要围绕近年来神经肌肉接头发育过程中若干重要信号通路以及相关神经肌肉系统疾病的主要研究进展进行综述。     

“星杂579”鸡视顶盖结构和突触类型的研究

本文应用透射电镜技术对“星杂579”鸡的视顶盖超徽结构和突触类型进行研究。结果表明,视顶盖的神经元有较丰富的细胞器。突触类型有轴-树突触、轴-轴突触,树-树突触、轴-轴-树串联突触、树-轴-树、轴-树-轴并联突触和轴一体突触。     

星形胶质细胞

目录一、星形胶质细胞的生物学特性(一 )星形胶质细胞的异质性(二 )胶质网络二、星形胶质细胞的功能(一 )分泌功能(二 )星形胶质细胞与神经的发育及再生(三 )星形胶质细胞具有对神经元微环境调控的能力(四 )免疫功能与血脑屏障调控三、星形胶质细胞功能的新近进展(一 )星形胶质细胞也具有可兴奋性(二 )星形胶质细胞与神经元的通讯或对话(三 )在突触形成和突触可塑性中的作用(四 )星形胶质细胞与神经发生胶质细胞是神经系统内数量众多的一大类细胞群体 ,约占中枢神经系统 (CNS)细胞总数的 90 % ,星形胶质细胞 (astrocyte)是其中主要的组成…     

猫丘脑腹后外侧核的超微结构

采用电镜技术观察了猫丘脑腹后外侧核的超微结构。该核内的神经元可分为大小两种类型，大型直径在１５—４０μｍ，小型小于１５μｍ，其胞质内容无明显差别。树突较多见，直径从１—１０μｍ不等。轴突可分为三种类型：含圆形小泡的小终末、终末及扁平小泡的终末。突触类型主要为轴树突触，此外还可见到轴体、轴轴、轴轴树、树树突触以及以树突为中心的突触复合体。在树突之间、树突与胞体之间还存在有非突触的丝状连接。     

脊髓胶状质内生长抑素免疫反应阳性结构与一级传入纤维之间的突触连接

本文用单纯免疫电镜及免疫电镜与溃变(后根切断术)相结合的方法,研究了一级传入纤维与脊髓胶状质内生长抑素(SOM)阳性结构之间的突触连结。结果在脊髓胶状质内观察到SOM阳性的胞体、轴突、树突及溃变的轴突,以上结构间形成了几种不同类型的突触连结:(1)Ⅰ型或Ⅱ型突触球的中央成份(CⅠ或CⅡ末梢)是溃变的或是SOM免疫反应阳性的,它们与周围的树突形成轴树突触、轴轴突触或树轴突触,其中有一些周围的树突还是SOM阳性的。(2)某些简单的轴突(不参与构成突触球的轴突)呈暗型溃变,并与SOM阳性的树突形成轴树突触。(3)简单的SOM阳性的致密型轴突与含SOM的树突或核周质形成轴树或轴体突触。(4)简单的SOM阳性的亮型轴突与含SOM的树突形成轴树突触。这些突触关系提示脊髓胶状质内SOM阳性树突和胞体可直接从一级传入纤维或脊髓后角固有神经元接受冲动,其中有一些一级传入纤维和脊髓后角固有神经元也是SOM阳性的。这表明在脊髓固有神经元与一级传入纤维之间及脊髓固有神经元本身都存在着自调节突触。本实验结果为SOM参与感觉信息的调节提供了超微结构证据。     

星形胶质细胞的生物学功能

人类大脑由两类细胞组成:一类是神经元,另一类是神经胶质细胞。神经胶质细胞的数量约为神经元的10倍,但其作用长期以来一直被认为仅限于在神经元之间充当填充物,填满大脑中的剩余空间,同时为神经元提供营养。但近年来认识到神经胶质细胞的主要成员星形胶质细胞能够感知外界刺激,它的反应选择性甚至高于相邻神经元。神经元的反应活动很多都要经过星形胶质细胞的介导才能完成。本文介绍了星形胶质细胞在神经调制、突触调节和神经血管系统偶联方面的一些新进展,以期在不久的将来对星形胶质细胞的功能有更深入的了解,并能应用于临床实践。     

大鼠孤束核内脑啡肽样免疫反应阳性结构及其轴突终末的突触联系

本文应用免疫细胞化学方法在光镜与电镜下观察了大鼠孤束核内脑啡肽样免疫反应（ＥＮＫ－ＬＩ）阳性结构的分布特征和ＥＮＫ－ＬＩ轴突终末的突触联系以及非突触性关系。结果表明：（１）经秋水仙素处理的大鼠,其孤束核内有许多ＥＮＫ－ＬＩ胞体的分布;而未经秋水仙素处理的大鼠,其孤束核内可见密集的ＥＮＫ－ＬＩ纤维与终末;ＥＮＫ－ＬＩ胞体、纤维和终末主要分布于锥体交叉平面至闩平面的孤束核内侧亚核与胶状质亚核。（２）ＥＮＫ－ＬＩ阳性产物主要定位于小圆形清亮囊泡外表面、大颗粒囊泡内和线粒体外表面等处。（３）ＥＮＫ－ＬＩ轴突终末主要与阴性树突形成轴－树突触。（４）阴性轴突终末终止于ＥＮＫ－ＬＩ轴突终末上,形成轴－轴突触。（５）ＥＮＫ－ＬＩ轴突终末与阴性轴突终末形成非突触性的轴－轴并靠。以上结果提示孤束核内的ＥＮＫ－ＬＩ神经成分主要通过突触后机制、也不排除突触前作用,参与孤束核中内脏信息的整合过程,而且这一作用又受到非ＥＮＫ－ＬＩ神经成分的调控。     

尼罗罗非鱼神经垂体的超微结构研究

尼罗罗非鱼神经垂体存在A_1、A_2和B型神经分泌纤维,其终端与腺细胞、毛细血管、组织间隔、基板或脑垂体细胞形成直接轴——腺突触联系、间接轴——腺联系和直接轴——脑垂体细胞突触联系,构成下丘脑对脑垂体腺细胞支配的三种联系形式。在神经垂体组织中还存在Ⅰ型和Ⅱ型两种结构和功能不同的脑垂体细胞。     

蒙古黄鼠（Citellus dauricus）松果腺的超微结构观察

The distal part of pineal gland of the Mongolian ground squirrel was ultrastructurally studied. The gland was composed of low electron-dense parenchymal cells, among which glial cells, pigment cells, blood vessels and neural elements were occasionally interspersed. The pinealocytes contained numerous mitochondria, lysosomes, microtubules, microfilaments, Golgi apparatus and free ribosomes, as well as less prominent profiles of rough- and smooth-surfaced endoplasmic reticula and some cilia, centrioles, synaptic ribbons and few subsurface cisterns. Some pinealocytes were vacuolated. The content of the vacuoles released into the extracellular space by exocytosis could be observed. The gap junctions between pinealocytes were also observed. Of particular interest was that many mitochondria "fused together" and formed gap junction-like structure in about five percent pinealocytes. The pigment cell has a amorphous nucleus which contains many aggregated chromatin, its cell membrane has a few microvilli projecting into a central lumen, these features may indicated that this kind of cell differs either from the pinealocyte or astrocyte. There are axo-axonic synapses or axo-dendritic synapses between neuron processes or between neuron processes and pinealocytes.     

A histochemical study of aldehyde fuchsin-positive material and "high-esterase cells" in the pineal gland of the Mongolian gerbil.

The pineal gland of the Mongolian gerbil consists of a superficial gland, stalk and deep pineal. The deep pineal differentiates postnatally. Histochemical studies of the superficial pineal gland indicate that it may be involved in the secretion of protein. Presumptive secretory material visualized by aldehyde fuchsin (AF) and chrome hematoxylin was observed along the course of blood vessels and among the pinealocytes. The distribution and texture of the AF-positive material was distinctive. It did not correspond to the pattern and texture of material stained with PAS, Sudan Black or acid orcein. Staining with AF was markedly reduced after incubation with trypsin, indicating that the AF-positive material is at least partially protein. The amount of stainable material increased with age. The AF-positive material was observed in what appeared to be interstitial or glial cells and processes, and in the processes of perivascular cells. Cells and fibrous processes with high non-specific esterase activity ("high-esterase cells") were observed among the pinealocytes and along the course of blood vessels. The distribution of the "high-esterase cells" and the morphology and texture of their esterase-containing processes were remarkably similar to the morphology and distribution of the material that stained with AF. It may be that the "high-esterase cells" contain AF-positive material. The "high-esterase cells" hydrolyzed both alpha-naphthyl acetate and alpha-naphthyl butyrate. The pinealocytes hydrolyzed only alpha-naphthyl acetate. The "high-esterase cells" appear to form a distinct class of cells within the superficial pineal gland. They are tentatively identified as a type of glial cell.     

Ultrastructure of the rat pineal stalk

The ultrastructure of the rat pineal stalk was described. The pineal stalk contained few pinealocytes, glial cells and numerous nerve fibers. The last were mostly non-myelinated axons, although a few myelinated ones were also observed. Glial cells showed many filaments, mostly in the processes which presented a longitudinal orientation. Other more lamellar processes were found enclosing the axons. The pineal stalk became wider as it reached the body of the gland. Ultrastructurally, this wide region resembled more the pineal body. Bundles of non-myelinated nerve fibers were seen around the pineal stalk.     

The pineal gland of the horse. Morphological and histochemical results. (With notes on the donkey and mule pineal)

The horse pineal gland has been investigated by morphological and histochemical methods. Particular care has been given to the cellular types, to the eventual presence of neurosecretory activity and to the nature of the pigments. Even in the horse pineal, it is possible to distinguish two populations of pinealocytes, morphologically but not histochemically distinct. A great number of pinealocytes are positive for the Masson- Hamperl reaction, and for Gomori- Bargmann 's chromic haematoxylin-phloxine and Gomori's paraldehyde-fuchsin. Along the connective septa, many brown- blackish pigmented cells were present; their pigment was positive for the Lillie and the Masson-Fontana reactions for the determination of melanin pigment. Another type of pigmented cells, carrying a brown yellowish pigment of lipofuscin nature was present, particularly in older animals, along the connective septa.     

The Pineal Gland of the Mink, Mustela vison: Light-, Fluorescence- and Electron Microscopical Studies

The pineal gland of normal and experimental female mink has been studied by light-, fluorescence- and electron microscopy. The general structure of the mink pineal is described. Two main cell types are recognized. One, termed pinealocyte, predominates in number. Though slight morphological differences (e.g. electron density of the cytoplasm and content of organelles) were observed, this study indicates that the pineal of mink only contains one single population of pinealocytes. The other, termed glial cell, inserted between the pinealocytes, is characterized by the presence of elongated processes, containing microfilaments. Different treatments (ovariectomy and LH—RH administration) and different endocrine states during the year induced morphological changes in the pinealocytes. A rich network of nerve fibres containing electron-dense granules (40–50 nm) is observed. Microspectrofluorometrically these fibres exhibit the spectral characteristics of cateholamines. All the pinealocytes show a yellow fluorescence. This cellular fluorophor shows the same microspectrofluorometric characteristics as does the fluorophor of serotonin. Occasionally, synaptic ribbons are observed in the perikaryon and the processes of the pinealocytes. A large number of cellular junctions between pinealocytes and endothelial cells is present. Their presumed function(s) are discussed. There is evidence of a blood-brain barrier within the mink pineal gland.     

Prenatal development of "synaptic" ribbons in the guinea pig pineal gland

Pineal "synaptic" ribbons are a heterogeneous population of organelles. "Synaptic" ribbons (SR) sensu stricto, "synaptic" spherules (SS), and intermediate forms (IMF) are present. Their function and origin are unknown, and a knowledge of their prenatal development is lacking. Thus the pineal glands of prenatal, neonatal, and adult guinea pigs were prepared for electron microscopy. "Synaptic" ribbons were studied morphologically and quantitatively. The three categories of "synaptic" ribbons reported in adult pineal glands were also present in prenatal pineal glands. Their structural features, distribution, grouping, and composition patterns are similar to those in adults. "Synaptic" ribbons were first detected in pinealocytes of the distal region of a 42-day postcoitus (PC) pineal gland and were comparable with those in adults. They increased in number with age and reached a peak at 63 days PC, followed by a steep decline at 66 and 67 days PC. By day 69 PC, the numbers increased again and showed a dramatic increase after birth. Several true ribbon synapses were seen at day 63 PC between pinealocyte cell processes or between pinealocyte cell process and pinealocyte cell body. Since true ribbon synapses have not been found in adult guinea pig pinealocytes, their synaptic nature could have been lost during development. No precursors for the "synaptic" ribbons were found. The endoplasmic reticulum cisternae may be the origin for the ribbon vesicles because of their close association with the "synaptic" ribbons.     

Interstitial and parenchymal cells in the pineal gland of the golden hamster

Summary A combined thin-section/freeze-fracture study was performed on the superficial pineal gland of the golden hamster, comparing the parenchymal and interstitial cells of this animal with those previously investigated in rats. In contrast to rats, no gap junctions and gap/tight junction combinations could be found between pineal parenchymal cells of the hamster. Furthermore, the interstitial cells of the hamster pineal gland were found to have large flat cytoplasmic processes, which abut over large areas equipped with tight junctions. In thin sections, profiles of interstitial cell processes were seen to surround groups of pinealocytes. Interstitial cells and their sheet-like, tight junction-sealed processes thus appear to delimit lobule-like compartments of the hamster pineal gland. Because the classification of the interstitial cells is uncertain, the expression of several markers characteristic of mature and immature astrocytes and astrocyte subpopulations has been investigated by indirect immunohistology. Many of the non-neuronal elements in the pineal gland are vimentin-positive glial cells, subpopulations of which express glial fibrillary acidic protein (GFA) and C1 antigen. The astroglial character of these cells is supported by the lack of expression of markers for neuronal, meningeal and endothelial cells. M1 antigen-positive cells have not been detected.Supported by a grant from Deutsche Forschungsgemeinschaft (Scha 185/9-2)     

Morphologic evidence of photoreceptor differentiation of pinealocytes in the neonatal rat

The pineal body and the retina of the neonatal Sprague-Dawley rat were studied by light and electron microscopy, and the morphologic differentiation of the parenchymal cells of the pineal body was compared with that of the developing photoreceptor cells of the retina. Between the ages of 4 and 12 days after birth, some of the developing pinealocytes were observed to become elongated and polarized, with their nuclei located at one pole. "Synaptic" ribbons were observed within the cell body. At the opposite pole the cells developed elongated cell processes that initially contained microtubules and ribosomes. These cell processes projected into luminal spaces and were attached by structures resembling zonulae adherentes to the adjacent cells. Extending from the tips of the cell processes, cilia with a 9 + 0 arrangement were observed. Lamellated and vesicular membranes were noted at the tips of the cilia. Such morphologic differentiation, however, could be observed only in rats younger than 17 days. Comparison of the morphologic features of the neonatal pinealocytes with those of the developing retinal photoreceptor cells showed much similarity. It is suggested that the pinealocytes of the neonatal rat undergo "photoreceptor-like" differentiation during a transient neonatal period. Such morphologic differentiation may provide an explanation for light-induced biochemical changes described in neonatal rats whose eyes had been enucleated.     

The expression of α-internexin and peripherin in the developing mouse pineal gland

Summary The mammalian pineal gland contains pinealocytes, interstitial glial cells, perivascular macrophages, neurons and neuron-like cells. The neuronal identity of neurons and neuron-like cells was an enigma. α-Internexin and peripherin are specific neuronal intermediate filament proteins and are expressed differentially in the CNS and PNS. We investigated the development of immunoreactivity and expression patterns of mRNAs for α-internexin and peripherin in the mouse pineal gland to determine the neuronal identity of these cells. Both α-internexin- and peripherin-immunoreactive cells were readily visualized only after birth. Both proteins were at the highest level on the postnatal day 7 (P7), rapidly declined at P14, and obtained their adult level at P21. Both protein and mRNA of α-internexin are expressed in some cells and nerve processes, but not all, of adult mouse pineal gland. Less number of peripherin immunoreactive or RNA-expressing cells and nerve processes were identified. Accumulations of α-internexin and peripherin proteins were also found in the cells from the aged pineal gland (P360). We concluded that some cells in the developing mouse pineal gland may differentiated into neurons and neuron-like cells expressing both α-internexin and/or peripherin only postnatally, and these cells possess dual properties of CNS and PNS neurons in nature. We suggested that they may act as interneurons between the pinealocyte and the distal neurons innervating the pinealocytes, or form a local circuitry with pinealocytes to play a role of paracrine regulatory function on the pinealocytes.     

Protein gene product (PGP) 9.5 immunoreactivity in nerve fibres and pinealocytes of guinea-pig pineal gland: interrelationship with tyrosine-hydroxylase- and neuropeptide-Y-immunoreactive nerve fibres

This light-microscopic (LM) immunohistochemical study has evaluated the presence and distribution of the pan-neural and neuroendocrine marker protein gene product (PGP) 9.5 in pinealocytes and nerve fibres of guinea-pig pineal gland. The pattern of PGP 9.5-immunoreactive (ir) nerve fibres has been compared with that of fibres staining for tyrosine hydroxylase (TH) or neuropeptide Y (NPY). The vast majority of pinealocytes stained for PGP 9.5, although with variable intensity. PGP 9.5 immunoreactivity was localized in pinealocytic cell bodies and processes. Double-immunofluorescence revealed that PGP 9.5 immunoreactivity was absent from glial cells identified with a monoclonal antibody against glial fibrillary acidic protein (GFAP), PGP 9.5 immunoreactivity was also present in a large number of nerve fibres and varicosities distributed throughout the pineal gland. The number of TH-ir and NPY-ir nerve fibres was lower compared with those containing PGP 9.5 immunoreactivity. All fibres staining for NPY also stained for TH. NPY-ir nerve fibres were found to be much more numerous than previously reported for this species. The double-immunofluorescence analysis indicated that almost all TH-ir nerve fibres of the pineal gland contained PGP 9.5 immunoreactivity. However, few PGP 9.5-ir nerve fibres, located in the periphery and the central part of the gland, were TH-negative. A large number of PGP 9.5-ir fibres was concentrated in the pineal stalk. In contrast, TH-ir and NPY-ir nerve fibres were rare in this part of the pineal gland. Our data provide evidence that immunohistochemistry for PGP 9.5 may be a useful tool further to differentiate central and peripheral origins of pineal innervation. Furthermore, the staining of pinealocytes for PGP 9.5 may be exploited to study the three-dimensional morphology and the architecture of pinealocytes and their processes under various experimental conditions.