Nervous tissue 高 志 华

教学要求 1、 熟悉神经组织的组成。 2、了解神经胶质细胞的分类与功能。 3、掌握神经元的形态结构、分类及突触的结构。 4、熟悉神经纤维的概念、无髓神经纤维与有髓神经纤维的区别。 5、熟悉神经末梢的概念、分类 与功能。 6、掌握血脑屏障的含义。　　　　　　　　　　　　

An outline Neurons Neuron-neuron communication (synapses) Glial cells Structure Soma Processes (neurites) Function Neuron-neuron communication (synapses) Classification Morphology transmitter Glial cells

The most fascinating structure in the world-brain The most fascinating structure in the world-brain! Consists of nervous tissue

Components of nervous tissue nerve cells: neuron, 1012 neurons in the human brain Glial cells: neuroglia Astrocytes Oligodendrocytes Microglia Schwan’s cells Function: Neurons: sense, receive, process information, initiate and conduct the nerve impulse Glial cells: support, protect, insulate and nourish neurons

synapse neuron neuron axon. neuroglia Axon terminal

Neuron 神经元 The structural and functional cellular unit By Ramon Cajal Osteon； neuron； nephron By Ramon Cajal

Structure of neurons: morphology cell body (soma), 5 um-150um spherical, pyramidal fusiform stellate in shape, Processes (neurites) dendrites: like branches of tree axon: long thin cord-liked process

Structure of neurons-the soma Cell membrane unit membrane-excitability, to receive stimuli, initiate and conduct nerve impulse membrane proteins- rich in ion channels and receptors

cell nuclei Structure of neurons-the soma large and round, centrally- located, less heterochromatin, so pale stained, with a large, clear nucleolus 核： 位于胞体中央，核大而圆，核仁明显。染色质细小呈松网状。

Structure of neurons-the soma cytoplasm: a.k.a.perikaryon (核周质) General structures: Mitochondria Lysosome Golgi complex Centromere Special structures Nissl body （尼氏体） Neurofibril (神经原纤维) Lipofuscin (脂褐素)

Nissl body (尼氏体) Structure LM: basophilic granules EM: parallel arrays of RERs and free ribosomes function: Protein synthesis structural proteins enzymes required for the production of neurotransmitters neuromodulators

Neurofibril 神经原纤维 LM：硝酸银染色可见 EM：神经丝、神经微管 功能：维持细胞形态支持 和运输物质

Other organelles Lipofuscin    Golgi apparatus mitochondria lysosomes

Structure of neurons-the processes Dendrites 树突: like branches of tree information input 1）一条以上并分枝 2）表面粗糙有树突棘, 3）接受刺激传导冲动到胞体。 Axon 轴突: long thin cord-liked process information output 1）一条，分支少，常在末端呈直角分出 2）轴丘(axon hillock)，无尼氏体，有神经原纤维 3）传出冲动。 Axon terminals Axon Dendrites

Dendrites 树突 many, short and more branches Contents: similar to the cell body function: receive information dendritic spines (树突棘) places for synapse formation Increase the surface volume

Axon 轴突 thin, less branch， the longest axon（siatic nerve） can reach ~1m no Nissl body have microtubules, neurofilaments, microfilaments, mitochondria, SER and vesicles axon hillock 轴丘: the initiating part of axon(no Nissl body) Axolemma 轴膜: membrane on the axon surface Axoplasm 轴浆：plasma within the axon Axon terminal ---function: To initiate and conduct the impulse axon hillock

Information flow through neurons

Axonal transport 轴突运输 slow anterograde 慢速轴突运输: cytoskeletal protein: microtubule, microfilament and neurofilament (0.1-0.4mm/d)细胞骨架结构（神经丝、神经微管） fast anterograde 快速顺向: synaptic vesicles, enzymes and proteins(100-400mm/d)轴膜更新所需的蛋白质、酶和神经递质 fast retrograde 快速逆向: products of metabolism, intaking materials including protein or neurotrophic factors (100-400mm/d)代谢产物，终末摄取物质 病毒感染，如狂犬病毒

Axonal transport

Classification 神经元分类 According to the number of processes 按突起分 multipolar neuron bipolar neuron pseudounipolar neuron 中枢突 外周突

Classification 神经元分类 According to function 按功能分 sensory neuron motor neuron interneuron

aminoacidergic neuron Classification 神经元分类 ---According to the neurotransmitter 按递质分 cholinergic neuron aminergic neuron peptidergic neuron aminoacidergic neuron

Classification 神经元分类 ---According to the length of axon Golgi type I neuron: long axon and large Golgi type II neuron: short axon

3. Synapse 突触

Synapse 突触 definition: the junctions between neurons or neuron and non-nerve cells 神经元与神经元之间、神经元和效应细胞（肌细胞、腺细胞）之间的一种特化的细胞连接，是传递信息的重要结构 classification: chemical synapse: taking neurotransmitter as communicating medium electrical synapse: gap junction,

化学性突触:占多数 形式 轴-体突触 轴-树突触 轴-轴突触 组成 EM:突触前成分 突触间隙(15-30nm) 突触后成分

---structure of chemical synapse: LM: in silver preparation, there are many bouton-liked structures on the surface of dendrites and cell body, called synaptic bouton

EM: presynaptic element: axonal terminal presynaptic membrane synapse vesicle: -round or flattened, 40-60nm -clear or with electron dense core synaptic cleft: 15-30nm postsynaptic element: postsynaptic membrane receptors

Classification of chemical synapse: According to function: excitatory synapse inhibitory synapse

4. Glial cell (neuroglia) 神经胶质细胞

神经胶质细胞(neuroglial cell) 分布在神经细胞之间,数量多。 功能:支持、营养、绝缘和形成隋鞘 （一）中枢神经胶质细胞 星形胶质细胞 少突胶质细胞 小胶质细胞 室管膜细胞 （二）周围神经胶质细胞 神经膜细胞 卫星细胞

function of Glial cell in CNS supporting, insulating and repairing regulate the environment and movement of neuron secret neurotrophic factor: nerve growth factor, ciliary neurotrophic factor and glial cell line-drived neurotrophic factor

Astrocytes 星型胶质细胞 large stellate round or ovoid nucleus, large and pale (euchromatin) glia filament: intermediate filament end feet: to form glia limitans or vascular feet - constitute blood brain barrier end feet

星形胶质细胞分类 纤维性：多在白质，突起细长，表面光滑 ，胶质丝多 原浆性：多在灰质，突起短粗，表面粗糙，胶质丝少 构成血脑屏障的胶质膜

fibrous 纤维性 protoplasmic 原浆性

smaller, fewer process with a small round and dark stained N Structure: smaller, fewer process with a small round and dark stained N Oligodendrocyte少突胶质细胞: Function: To form myelin-sheath of NF in CNS

Microglia小胶质细胞 structure: smallest, elongate shape or ovoid, with a small dark irregular N function: phagocytosis - mononuclear phagocyte system

Ependymal cell 室管膜细胞 structure: simple cuboidal or columnar epi apical: microvilli and cilia basal: long processes function: produce cerebrospinal fluid nerve stem cell in or under ependyma distribution: ventricle of brain and central canal of spinal cord

glial cell in PNS (peripheral nervous system) 神经膜细胞(Schwann cell)：形成周围神经纤维的髓鞘。 神经节胶质细胞（卫星细胞）：神经节内包裹神经元胞体的胶质细胞，又称被囊细胞。

Nerve fiber 神经纤维 definition: a structure formed by axon and glial cell can conduct the impulse to certain direction ---classification: according to myelin-sheath myelinated nerve fiber有髓神经纤维 unmyelinated nerve fiber无髓神经纤维

1)      myelinated nerve fiber (MNF) ① MNF in PNS LM: Axon myelin-sheath: HE: net-liked; OsO4(osmium tetroside) fixation and stain: black with Schmidt-Lantermann incisure neurilemma: cell membrane of Schwann and basement membrane

Ranvier node: narrow part, no myelin-sheath-saltatory conduction internode: the segment of NF between two Ranvier nodes

Ranvier nodes Axon

有髓神经纤维 myelinated nerve fiber 组成：轴突＋髓鞘＋神经膜 神经胶质细胞 周围：神经膜细胞 Schwann xbao 中枢：少突胶质细胞

有髓神经纤维 组成：轴突＋髓鞘＋神经膜

有髓神经纤维与无髓神经纤维横切

神经（nerve） 周围神经纤维束平行排列，外包结缔组织膜而成的索状结构。 神经外膜（epineurium） 神经束膜（perineurium） 神经内膜（endoneurium）

神经末梢(never ending) 定义：周围神经纤维的终末部分终止于其 他组织中所构成的特殊结构。 分类： 感觉神经末梢 运动神经末梢

感觉神经末梢 1.游离神经末梢：冷、热、痛 2.有被囊的感觉神经末梢：触觉小体 环层小体 肌梭 运动神经末梢 运动终板

游离神经末梢 无髓腔而裸露部分。感觉冷热、疼痛等

被囊神经末梢 触觉小体、环层小体、肌梭

运动神经末梢 定义：运动神经元的轴突分布骨骼肌、平滑肌及腺内并与其他组织共同构成的结构 分类： 内脏运动神经未梢 躯体运动神经未梢

内脏运动神经末梢 分布于心肌、平滑肌及腺细胞的植物神经未端分支，未梢形成串珠状或呈膨大小结。

躯体运动神经末梢（运动终板） 支配骨骼肌，形成突触前膜、突触间隙、突触后膜。

血脑屏障（blood-brain barrier） 组成： 连续毛细血管内皮 基膜 神经胶质膜 功能： 限制有害物质进入脑神经组织

施万细胞 神经纤维

Neurofibril LM: shown ony by silver impregnation methods as a network formed thread-liked dark brown structures (2-3 um)

Love your cells Love your tissues Love yourself Love histology!

Neurofibril LM: shown ony by silver impregnation methods as a network formed thread-liked dark brown structures (2-3 um)

dendrite axon