共查询到20条相似文献，搜索用时 46 毫秒
1.
Substance P activity in the bullfrog retina: localization and identification in several vertebrate species 总被引：1，自引：0，他引：1
Immunoreactive substance P is present in the bullfrog retina, possibly in two types of stratified amacrine cells, with their somas in the inner nuclear layer and their neuronal processes entering the inner plexiform layer and ramifying in sublayers 3 or 4 (or both). Occasionally, polygonal somas positive for substance P were found in the ganglion cell layer. Approximately 75 percent of the cell bodies positive for substance P and 65 percent of the radioimmunoassayable substance P were found in the superior half of the frog retina. On the basis of high-performance liquid chromatography, the immunoreactive substance P in the neural retina of the rat, monkey, or chick is similar to synthetic substance P, whereas this is not true of the immunoreactive substance P in the bullfrog or carp retina. 相似文献
2.
Rod and cone pathways in the inner plexiform layer of cat retina 总被引：9，自引：0，他引：9
In cat retina, rod bipolar terminials do not synapse on ganglion cells but on two types of amacrine cell (types I and II). Cone bipolars synapse directly on ganglion cells and on type I amacrines. The type II amacrine appears to play a special internuncial role between bipolars and ganglion cells in the rod system. 相似文献
3.
Unusual retinal cells in the dolphin eye 总被引：1，自引：0，他引：1
By comparison to the cellular constituents of the retinas of certain other diving mammals, the elements of the dolphin retina include an unusually large number of specialized cells. Both cone and rod receptors may be identified. An unusual amacrine cell may be seen which produces a process that spans the cells between the inner plexiform and outer plexiform layers. Most unusual is a layer of giant ganglion cells which appears to serve most of the central retina. The giant ganglion cells support giant dendrites and optic nerve fibers which range up to 8 micrometers in diameter. 相似文献
4.
Nicotinic antagonists enhance process outgrowth by rat retinal ganglion cells in culture 总被引：2，自引：0，他引：2
S A Lipton M P Frosch M D Phillips D L Tauck E Aizenman 《Science (New York, N.Y.)》1988,239(4845):1293-1296
Functional nicotinic cholinergic receptors are found on mammalian retinal ganglion cell neurons in culture. The neurotransmitter acetylcholine (ACh) can be detected in the medium of many of these retinal cultures, after release presumably from the choline acetyltransferase-positive amacrine cells. The postsynaptic effect of endogenous or applied ACh on the ganglion cells can be blocked with specific nicotinic antagonists. Here it is shown that within 24 hours of producing such a pharmacologic blockade, the retinal ganglion cells begin to sprout or regenerate neuronal processes. Thus, the growth-enhancing effect of nicotinic antagonists may be due to the removal of inhibition to growth by tonic levels of ACh present in the culture medium. Since there is a spontaneous leak of ACh in the intact retina, the effects of nicotinic cholinergic drugs on process outgrowth in culture may reflect a normal control mechanism for growth or regeneration of retinal ganglion cell processes that is exerted by ACh in vivo. 相似文献
5.
The activity of acetylcholinesterase in the inner plexiform layer of the rabbit retina was not affected detectably by prior section of the optic nerve. After the animals were treated with diisopropyl phosphorofluoridate, acetylcholinesterase reappeared in the somata of the amacrine cells and in certain cells of the ganglion cell layer before it reappeared in the inner plexiform fibers. This confirms the normal presence of acetylcholinesterase at the former site. The possible role of acetylcholine in intraretinal transmission is considered. 相似文献
6.
Lateral interactions at inner plexiform layer of vertebrate retina: antagonistic responses to change 总被引：5，自引：0，他引：5
F S Werblin 《Science (New York, N.Y.)》1972,175(25):1008-1010
Lateral interactions at the inner plexiform layer of the retina of the mudpuppy were studied intracellularly after they were isolated from interactions at the outer plexiform layer with a special stimulus. The isolation was confirmed by recording no surround effect at bipolar cells under conditions that elicited a strong surround effect at ganglion cells. It appears that amacrine cell, which respond to spatiotemporal change at one retinal region, inhibit the response to change in on-off ganglion cells at adjacent sites. 相似文献
7.
D I Vaney 《Science (New York, N.Y.)》1986,233(4762):444-446
Neurons that accumulate the transmitter serotonin have been identified in the living retina by being labeled with 5,7-dihydroxytryptamine (5,7-HT), an autofluorescent serotonin analog. Iontophoretic injection of Lucifer yellow into the labeled cells under microscopic control revealed that the serotonin-accumulating neurons in rabbit retina constitute two morphological types of amacrine cells, termed S1 and S2, whose distal dendrites are stratified at the inner margin of the inner plexiform layer. The dendritic overlap of the S1 type is extraordinarily large: each point on the retina is covered by the fields of 550 to 900 S1 amacrines, and 6 to 8 meters of their dendrites are packed into each square millimeter of retina. Such a pervasive neuropil may provide an effective substrate for diffuse transmitter release, as proposed for serotonergic fibers elsewhere in the central nervous system. 相似文献
8.
A small amount of horseradish peroxidase, injected into the goldfish optic nerve and transported into the retina, filled an annulus of ganglion cells. Since the retina grew by annular addition of cells, this result shows that axons from cells of similar age clustered together in the nerve. 相似文献
9.
Kim J Wu HH Lander AD Lyons KM Matzuk MM Calof AL 《Science (New York, N.Y.)》2005,308(5730):1927-1930
The orderly generation of cell types in the developing retina is thought to be regulated by changes in the competence of multipotent progenitors. Here, we show that a secreted factor, growth and differentiation factor 11 (GDF11), controls the numbers of retinal ganglion cells (RGCs), as well as amacrine and photoreceptor cells, that form during development. GDF11 does not affect proliferation of progenitors-a major mode of GDF11 action in other tissues-but instead controls duration of expression of Math5, a gene that confers competence for RGC genesis, in progenitor cells. Thus, GDF11 governs the temporal windows during which multipotent progenitors retain competence to produce distinct neural progeny. 相似文献
10.
Retrograde axonal transport in the central nervous system 总被引：18，自引：0，他引：18
When horseradish peroxidase is injected into the optic tectum of a chick, axons of ganglion cells transport it centripetally to their cell bodies in the retina at a rate of about 72 millimeters per day. After intraocular injections in the young chick, the peroxidase is transported centripetally along efferent axons, and is concentrated in cell bodies within the isthmo-optic nucleus. This retrograde movement of protein from axon terminal to cell body suggests a possible mechanism by which neurons respond to their target areas. 相似文献
11.
白藜芦醇对肝癌SMMC-7721细胞的抑制作用 总被引：2，自引：1，他引：1
[目的]探讨白藜芦醇对人肝癌细胞SMMC-7721体外生长的影响和作用机制。[方法]利用MTT法检测不同剂量组的白藜芦醇对肝癌细胞SMMC-7721细胞增殖的影响,通过Hoechst染色和荧光显微镜观察肝癌细胞SMMC-7721细胞核的形态学变化,流式细胞仪测定各浓度组白藜芦醇对肝癌细胞SMMC-7721作用的周期变化与凋亡分析。[结果]白藜芦醇对人体肝癌细胞SMMC-7721的增殖具有抑制作用,且有浓度和时间依赖性;在荧光显微镜下观察到典型的凋亡细胞形态特征;流式方法测定的结果显示,白藜芦醇阻滞肝癌细胞SMMC-7721于S期。[结论]白藜芦醇对人体肝癌细胞SMMC-7721生长具有抑制作用,使其细胞周期阻滞于S期并诱导其凋亡。 相似文献
12.
Huberman AD Wang GY Liets LC Collins OA Chapman B Chalupa LM 《Science (New York, N.Y.)》2003,300(5621):994-998
The segregation of initially intermingled left and right eye inputs to the dorsal lateral geniculate nucleus (DLGN) during development is thought to be in response to precise spatial and temporal patterns of spontaneous ganglion cell activity. To test this hypothesis, we disrupted the correlated activity of neighboring ganglion cells in the developing ferret retina through immunotoxin depletion of starburst amacrine cells. Despite the absence of this type of correlated activity, left and right eye inputs segregated normally in the DLGN. By contrast, when all spontaneous activity was blocked, the projections from the two eyes remained intermingled. Thus, certain features of normal neural activity patterns are not required for the formation of eye-specific projections to the DLGN. 相似文献
13.
1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine destroys dopamine neurons in explants of rat embryo mesencephalon 总被引：11，自引：0，他引：11
Explants of embryonic rat mesencephalon were grown in organotypic culture. Addition of 10 microM 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to the culture medium for 4 to 7 days resulted in loss of dopamine cell bodies and fiber outgrowths, as observed by fluorescence histochemistry. At the same time, the cultures showed decreased uptake of tritium-labeled dopamine. However, no signs of generalized toxicity were evident when the explant cultures were viewed by light and phase-contrast microscopy. These results show that MPTP exerts a relatively selective destructive action in dopamine neurons in vitro, similar to the action observed in humans and monkeys in vivo. Pargyline (10 microM), a monoamine oxidase inhibitor, protected the dopamine neurons in the explants. Organotypic cultures provide an experimental model for the study of the properties of MPTP in vitro. 相似文献
14.
The percentage of bipolar and amacrine synapses onto ganglion cell dendrites of the ground squirrel has been determined by electron microscopy of cells impregnated by the Golgi method. One group of ganglion cells has mainly amacrine input (approximately 97 percent); the other group has an approximately equal bipolar and amacrine input. Morphologically distinct types of ganglion cells usually have a consistent synaptic input, but exceptions may exist. 相似文献
15.
鳜仔鱼视网膜及口腔齿的发育对摄食的适应 总被引：1，自引：0，他引：1
采用石蜡切片及HE染色的方法对鳜受精卵及1～30 d仔鱼的视网膜结构和视觉特性进行研究,结果表明:(1)受精后54 h晶状体形成,视网膜还未分化;80 h视网膜分化为外核层、内核层、内网层和神经节细胞层4层结构;98 h形成色素上皮层、视杆视锥层和神经纤维层;124 h外网层形成,视网膜10层结构发育完全。孵化后4 d开始出现少量颌齿和咽齿;5 d和14 d分别观察到腭齿和犁齿;15d时鳃耙形成但形状较小。口腔齿的数量随着仔鱼个体的生长而增加至近于成体。(2)鳜内核层分化成一层水平细胞、数层双极细胞和无长突细胞,属光感受系统不发达的类型。(3)鳜仔鱼在消化系统尚未发育完全时已经开始形成口腔齿,为提高捕食的成功率提供了基础条件,充分表现了个体发育在进化过程中与生存环境相适应的特点。(4)鳜神经节细胞层细胞随个体的生长发育而减少,孵化后29 d,体长18.36 mm时,只有一层神经节细胞,说明此时的仔鱼已适应黑暗环境生活。鳜视觉结构的变化与其从浮游到底层的生态迁移及捕食方式的变化相适应。研究亮点:从组织学研究角度对鳜仔鱼视网膜发育进行了探讨,详细研究了视网膜各组成结构的发育特征,并结合鳜仔鱼齿的发育特征,分析了其对摄食行为的适应,首次解释了伴随着视网膜发育而形成的由浮游生活到底层生活的适应,研究结果以期为鳜在种苗生产过程中正确选择开口饵料和早期动物性饵料,以降低种苗的死亡率等提供理论依据。 相似文献
16.
Induction of glutamine synthetase in embryonic retina: its dependence on cell interactions 总被引：5，自引：0，他引：5
A relation between enzyme induction in embryonic cells and cellular organization is indicated by the finding that the levels of glutamine synthetase induced by hydrocortisone in the embryonic neural retina in vitro are dependent on the associations between the retina cells. Intact retina tissue, aggregates of dissociated cells, and cells in monolayer culture showed a decreasing response, in this order, to glutamine synthetase induction. With time of culture, the enzyme activity continued to rise in the intact retina and in cell aggregates, but activity declined in monolayer cultures even though the inducer was continuously present. Dispersed cells cultured in monolayer without the inducer showed after 24 hours a loss of inducibility which could not be reversed by reaggregating such modified cells but could be prevented by maintaining the freshly dispersed cells at a low temperature. 相似文献
17.
The central nervous system (CNS) loses the ability to regenerate early during development, but it is not known why. The retina has long served as a simple model system for study of CNS regeneration. Here we show that amacrine cells signal neonatal rat retinal ganglion cells (RGCs) to undergo a profound and apparently irreversible loss of intrinsic axon growth ability. Concurrently, retinal maturation triggers RGCs to greatly increase their dendritic growth ability. These results suggest that adult CNS neurons fail to regenerate not only because of CNS glial inhibition but also because of a loss of intrinsic axon growth ability. 相似文献
18.
In order to observe the role of calcium ion in apoptosis of MD cancer cells induced by arsenic trioxide, inhibition percentage was detected by MTT assay; morphology changes were examined by fluorescence microscope; apoptosis was examined by DNA Ladder; [Ca^2＋]i was investigated by spectrofluorimeter in vitro on MDCC-MSB 1 cells. The results showed that As2O3 inhibited the proliferation of MDCC-MSB1 cells in concentration dependent manner （P〈0.05 or P〈0.01）; typical apoptosis character was observed by fluorescence microscope; DNA Ladder was observed; the [Ca^2＋]i was elevated significantly after the treatment of As203 （P〈0.05 or P〈0.01） and showed a dose-dependent manner. It is concluded that the calcium may play an important role in apoptosis of MD cancer cells induced by arsenic trioxide. 相似文献
19.
奶牛小肠上皮细胞的原代培养和鉴定 总被引：1，自引：0，他引：1
为研究小肽转运蛋白对小肽转运和吸收机制提供细胞模型,在体外建立原代奶牛小肠上皮细胞分离的方法,采用Ⅰ型胶原酶和中性蛋白酶混合消化液对奶牛小肠组织进行消化,通过2%山梨醇进行密度梯度离心以去除单核细胞、淋巴细胞和肌细胞;用刮除法、相差消化法和96孔板单克隆方法来纯化奶牛小肠上皮细胞,从细胞形态学、细胞角蛋白18免疫荧光染色和小肠上皮细胞特异性标志蛋白来鉴定奶牛肠上皮细胞。结果表明:1)采用Ⅰ型胶原酶和中性蛋白酶联合消化奶牛小肠组织,通过2%山梨醇密度梯度离心可以获得大量的细胞团且48h发生贴壁,但是细胞贴壁不牢。2)48h之后细胞团进一步向外辐射生长出细胞,细胞形态呈现典型的上皮细胞和铺路石形态。5~7d细胞处于对数生长期,细胞大量增值,一部分成纤维细胞与小肠上皮细胞夹杂生长。3)通过96孔板能够单克隆奶牛小肠上皮细胞,细胞呈现均一的铺路石形态。4)奶牛小肠上皮细胞角蛋白18鉴定为阳性,荧光显微镜下能够发出绿色荧光。5)通过RT-PCR能够检测到奶牛小肠上皮细胞特异性标志蛋白E-钙黏蛋白、碱性磷酸酶和肠肽酶的表达,成功建立了奶牛小肠上皮细胞的分离和培养方法。 相似文献
20.
Tropepe V Coles BL Chiasson BJ Horsford DJ Elia AJ McInnes RR van der Kooy D 《Science (New York, N.Y.)》2000,287(5460):2032-2036
The mature mammalian retina is thought to lack regenerative capacity. Here, we report the identification of a stem cell in the adult mouse eye, which represents a possible substrate for retinal regeneration. Single pigmented ciliary margin cells clonally proliferate in vitro to form sphere colonies of cells that can differentiate into retinal-specific cell types, including rod photoreceptors, bipolar neurons, and Müller glia. Adult retinal stem cells are localized to the pigmented ciliary margin and not to the central and peripheral retinal pigmented epithelium, indicating that these cells may be homologous to those found in the eye germinal zone of other nonmammalian vertebrates. 相似文献