刺参(Stichopus japonicus Selenka)血淋巴细胞的超微结构观察

根据细胞的形态结构特征,在电镜水平上将刺参血淋巴细胞分为4种基本类型:大颗粒细胞、小颗粒细胞、透明细胞、淋巴样细胞。大颗粒细胞呈圆球形、椭球形,直径6.8～12.8μm,内具粗大的胞质颗粒,细胞质及细胞器极少。小颗粒细胞圆球形,直径4.8～11.0μm,含有大量结构均匀、电子密度较高的胞质小颗粒,同时还含有较丰富的线粒体、内质网等细胞器。透明细胞直径4.8～10.2μm,形态不规则,易变形伸出胞突;胞质丰富,内含大量的线粒体、内质网、溶酶体及吞饮小泡等。淋巴样细胞直径4.2～5.3μm,呈圆球形,核较大,胞质较少,仅见极少量的细胞器。     

双峰驼血管的组织与超微结构观察

采用光镜、电镜及特殊染色方法研究了内蒙古阿拉善右旗５例双峰驼大、中、小动脉与静脉以及毛细血管的微细结构,结果表明,各级动脉与静脉均可分为内膜、中膜和外膜３层。在大动脉,３层中均有弹性膜和弹性纤维,其间界限不甚明显。中动脉与小动脉属肌性动脉,中膜平滑肌厚而明显。中动脉外膜内层结构致密,纤维组织丰富。大静脉的内膜与中膜均较薄,中膜由数层平滑肌构成,外膜则很厚,由大量平滑肌束及胶原纤维、弹性纤维构成。中静脉中膜仅由数层平滑肌构成;外膜厚,弹性纤维丰富。小静脉管管壁的结构与中静脉的相似,但较薄。毛细血管管壁也较厚,内皮细胞呈高突状,胞质中常有许多质膜小泡。毛细血管管腔狭小,管腔内有红细胞时,毛细血管内界不明显。     

Electron microscopy: two major synaptic types on spinal motoneurons

Two major types of synaptic bulbs are defined on the motoneuron surface of the monkey, on the basis of content of agranular "synaptic" vesicles of two distinct kinds. Both types are present on dendritic as well as perikaryal surface. Because of the approximately equal numbers, the hypothesis that one type is excitatory and the other inhibitory naturally arises.     

Synaptic potentials recorded in cell cultures of nerve and muscle

Initially dissociated spinal cord and muscle cells derived from chick embryos differentiate sufficiently in tissue culture to form functional synaptic contacts. Spontaneous and evoked potentials recorded with intracellular microelectrodes resemble synaptic responses of adult spinal cord and neuromuscular junctions.     

Developing neuromuscular junctions: first signs of chemical transmission during formation in tissue culture

Electrophysiological study of rat neuromuscular junctions in the early stage of formation in tissue culture showed that chemical transmission begins with discrete, localized release of transmitter about the time when nerve-muscle contacts are first visible with light microscopy. Noncontractile myotubes with as few as three nuclei showed evidence of junctional transmission.     

背角无齿蚌(Anodonta woodiana)血细胞的分类

用光学显微镜和透射电子显微镜对背角无齿蚌血细胞进行观察.结果发现,体长6～12cm的背角无齿蚌血细胞浓度为(2.42±0.38)×106/mL.根据细胞质内颗粒出现情况,将该蚌血细胞分为两大类,即颗粒细胞和无颗粒细胞.颗粒细胞明显的特征是细胞质中存在许多颗粒,无颗粒细胞的特征是细胞质中不含有或含有少量颗粒.根据颗粒细胞的体积和胞质内颗粒的大小还可以将其分为大颗粒细胞和小颗粒细胞(分别占4.28%和59.28%).根据无颗粒细胞的大小和核质比的不同将其分为透明细胞和淋巴样细胞(分别占27.74%与8.70%).4种类型的血细胞对Wrights染料有不同的亲和性,大颗粒细胞表现为嗜酸性,小颗粒细胞与透明细胞均呈现嗜酸性和嗜碱性两种,淋巴样细胞表现为嗜碱性.     

鸡肠道组织中血管活性肠肽的分布特点

为探讨鸡肠道组织中肽能神经支配的途径及其功能,运用免疫组织化学超敏SP法,对不同生长阶段鸡肠道中血管活性肠肽(Vasoactive intestinal peptide,VIP)的分布特点进行了研究。结果显示,肠壁中VIP的表达范围较为广泛,涉及黏膜上皮和固有层、肌层和外膜,尤以固有层和肌层最为典型;随着日龄增加,黏膜上皮间VIP阳性细胞数量逐渐增多;从肠道不同部位的分布来看,十二指肠中VIP的表达强于同时期其他部位,空肠中的表达次之,回肠和盲肠的表达相对较弱。黏膜固有层和肌层一直分布有染色较深的VIP阳性神经纤维,呈串珠状、细线状或膨体状。提示鸡肠道是产生VIP的又一个重要部位,肠道中的VIP可参与鸡免疫器官的功能调节,并作为一种信息分子介导神经内分泌系统和黏膜免疫系统之间的相互作用。     

中华绒螯蟹大颚器官及眼柄因子对其影响的研究

透射电镜观察了中华绒螯蟹（Ｅｒｉｏｃｈｅｉｒ　ｓｉｎｅｎｓｉｓ）大颚器官及眼柄切除后对其超微结构的影响。大颚器官由许多细胞团组成,细胞团间有血淋巴通道和血淋巴窦。细胞团内的细胞呈放射状排列,细胞核位于向心端,密集的异染色体聚集在周边核质,细胞质内有两种不同类型的无颗粒内质网及大量形状各异的线粒体。细胞膜和血淋巴通道连接时,呈不同程度的内陷和褶皱。这些超微结构特点明显与合成甾类化合物的细胞特点一致。眼柄切除后,其结构出现了几种变化：无颗粒内质同数量减少,线粒体膨大,空泡数量增多,可能是大颚器官分泌活动增强所致。     

Acetylcholine and cholinacetylase content of synaptic vesicles

Acetylcholine, cholinacetylase, and acetylcholinesterase were determined in three subfractions that resulted from the osmotic shock of the "mitochondrial" fraction of the rat brain. Acetylcholine and cholinacetylase were found concentrated in the subfraction that contained mainly synaptic vesicles and some membranes, whereas the larger proportion of the acetylcholinesterase was observed in the subfraction that contained torn nerve endings. These results support the idea that synaptic vesicles are the morphological units of acetylcholine within the synapse.     

Bruchpilot promotes active zone assembly, Ca2+ channel clustering, and vesicle release

The molecular organization of presynaptic active zones during calcium influx-triggered neurotransmitter release is the focus of intense investigation. The Drosophila coiled-coil domain protein Bruchpilot (BRP) was observed in donut-shaped structures centered at active zones of neuromuscular synapses by using subdiffraction resolution STED (stimulated emission depletion) fluorescence microscopy. At brp mutant active zones, electron-dense projections (T-bars) were entirely lost, Ca2+ channels were reduced in density, evoked vesicle release was depressed, and short-term plasticity was altered. BRP-like proteins seem to establish proximity between Ca2+ channels and vesicles to allow efficient transmitter release and patterned synaptic plasticity.     

High-probability uniquantal transmission at excitatory synapses in barrel cortex

The number of vesicles released at excitatory synapses and the number of release sites per synaptic connection are key determinants of information processing in the cortex, yet they remain uncertain. Here we show that the number of functional release sites and the number of anatomically identified synaptic contacts are equal at connections between spiny stellate and pyramidal cells in rat barrel cortex. Moreover, our results indicate that the amount of transmitter released per synaptic contact is independent of release probability and the intrinsic release probability is high. These properties suggest that connections between layer 4 and layer 2/3 are tuned for reliable transmission of spatially distributed, timing-based signals.     

蛇毒突触前磷脂酶A_2神经毒素的作用机制研究进展

蛇毒突触前磷脂酶A2神经毒素(Snake presynaptic phospholipase A2 neurotoxins,SPANs)是蛇毒中毒性最大的成分之一,主要作用于脊椎动物神经-肌肉接头(Neuromuscular junction,NMJ)处,阻断神经递质乙酰胆碱的释放致使动物肌肉麻痹、呼吸衰竭直至死亡。SPANs与突触前膜特异性结合,水解膜磷脂生成溶血磷脂(Lysophospholipids,LysoPC)和脂肪酸(Fatty acids,FA),改变膜构象、膜通透性提高导致Ca2+大量内流至神经末梢、突触囊泡(Synaptic vesicles,SV)枯竭、线粒体功能障碍等。对蛇毒突触前磷脂酶A2神经毒素的受体分子及其引发的一系列胞内分子事件进行综述。     

绵羊8—16细胞胚胎的超微结构

利用透射电镜技术研究了绵羊８－１６细胞胚胎的超微结构，并与２细胞胚胎作了比较．结果表明，８－１６细胞胚胎卵裂球间以间隙连接联系，胞质主要成分是一种带有界膜的囊泡，线粒体丰富，以带帽线粒体为主，也有少量横嵴线粒体，１６细胞胚胎中，后者的比例高于８细胞胚胎．与２细胞胚胎相比，８─１６细胞胚胎的高尔基体发达．但滑面内质网数量减少、８细胞胚胎卵裂球具有数个致密的球形或环形核仁前体，１６细胞胚胎的核仁中出现次级小泡腔，标志着ｒＲＮＡ开始合成．     

Equivalent effects of snake PLA2 neurotoxins and lysophospholipid-fatty acid mixtures

Snake presynaptic phospholipase A2 neurotoxins (SPANs) paralyze the neuromuscular junction (NMJ). Upon intoxication, the NMJ enlarges and has a reduced content of synaptic vesicles, and primary neuronal cultures show synaptic swelling with surface exposure of the lumenal domain of the synaptic vesicle protein synaptotagmin I. Concomitantly, these neurotoxins induce exocytosis of neurotransmitters. We found that an equimolar mixture of lysophospholipids and fatty acids closely mimics all of the biological effects of SPANs. These results draw attention to the possible role of local lipid changes in synaptic vesicle release and provide new tools for the study of exocytosis.     

Destruction of mammalian motor nerve terminals by black widow spider venom

Black widow spider venom selectively poisons motor nerve endings. A progressive and irreversible failure of neuromuscular transmission occurs in the cat. Electron microscopy of the poisoned nerve-muscle junction shows a sequence of motor nerve ending damage that culminates in disruption of the prejunctional membrane and loss of all organelles, including synaptic vesicles. The postjunctional membrane was morphologically unaffected. After complete poisoning, the contractile response to exogenous acetylcholine was severely impaired, an indication that the prejunctional site is chiefly involved in the contractile response produced by exogenous acetylcholine and that the pre- and postjunctional effects of acetylcholine were separated.     

Neurexin and neuroligin mediate retrograde synaptic inhibition in C. elegans

The synaptic adhesion molecules neurexin and neuroligin alter the development and function of synapses and are linked to autism in humans. Here, we found that Caenorhabditis elegans neurexin (NRX-1) and neuroligin (NLG-1) mediated a retrograde synaptic signal that inhibited neurotransmitter release at neuromuscular junctions. Retrograde signaling was induced in mutants lacking a muscle microRNA (miR-1) and was blocked in mutants lacking NLG-1 or NRX-1. Release was rapid and abbreviated when the retrograde signal was on, whereas release was slow and prolonged when retrograde signaling was blocked. The retrograde signal adjusted release kinetics by inhibiting exocytosis of synaptic vesicles (SVs) that are distal to the site of calcium entry. Inhibition of release was mediated by increased presynaptic levels of tomosyn, an inhibitor of SV fusion.     

Quantal release of transmitter is not associated with channel opening on the neuronal membrane

The traditional view that quantal release of neurotransmitter results from the fusion of transmitter-containing vesicles with the neuronal membrane has been recently challenged. Although various alternative mechanisms have been proposed, a common element among them is the release of cytoplasmic transmitter, which, in one view, could occur through large conductance channels on the presynaptic membrane. Six nerve-muscle cell pairs were examined with a whole-cell patch clamp for the presence of such channels that are associated with the production of miniature end-plate potentials. Examination of the neuronal membrane current during the occurrence of 822 miniature end-plate potentials produced no evidence of large channels. Thus it is unlikely that quantal release is mediated by such channels in the neuromuscular junction.     

猪输卵管组织结构的研究

采用石蜡切片,H.E染色,对猪输卵管进行显微观察和研究.结果表明:输卵管伞和漏斗部均为膜性结构.输卵管伞由内、外侧的假复层纤毛柱状上皮和中央的琉松结缔组织共同构成,没有肌层和外膜;漏斗部、壶腹部和峡部均由黏膜层、肌层币口外膜3层构成.     

Visualization and functional analysis of RNA-dependent RNA polymerase lattices

Positive-strand RNA viruses such as poliovirus replicate their genomes on intracellular membranes of their eukaryotic hosts. Electron microscopy has revealed that purified poliovirus RNA-dependent RNA polymerase forms planar and tubular oligomeric arrays. The structural integrity of these arrays correlates with cooperative RNA binding and RNA elongation and is sensitive to mutations that disrupt intermolecular contacts predicted by the polymerase structure. Membranous vesicles isolated from poliovirus-infected cells contain structures consistent with the presence of two-dimensional polymerase arrays on their surfaces during infection. Therefore, host cytoplasmic membranes may function as physical foundations for two-dimensional polymerase arrays, conferring the advantages of surface catalysis to viral RNA replication.     

Uptake of isolated chloroplasts by mammalian cells

Mouse fibroblasts (L cells) in suspension culture incorporated isolated chloroplasts of spinach and African violets and isolated mitochondria of chicken liver. The organelles resided in the cell cytoplasm and were not contained in vacuoles or digestion vesicles. Green cells divided like normal cells. Green chloroplasts were followed for five cell generations or 5 days, at which time hybrid cells were greatly outnumbered by nongreen progeny cells. The ingested chloroplasts retained their structural integrity as determined by electron microscopy of organelles and hybrid cells and by analysis of photochemical activity and DNA in chloroplasts reisolated from cells after 1 or 2 days in culture.