Neuron Neuron Neuroglia (glia)Neuroglia (glia)

PNS :PNS : Schwann cells Schwann cells

Satellite cellsSatellite cells

CNS :CNS :AstrocytesAstrocytes

OligodendrocytesOligodendrocytes

Microglial cells Microglial cells

Ependymal cells Ependymal cells

Composition of Nervous TissueComposition of Nervous Tissue

1. Neurons have1. Neurons have TWOTWO kinds of “processes” called axons kinds of “processes” called axons

and dendritesand dendrites ，， but Glial cells only havebut Glial cells only have ONEONE. .

2. Neurons2. Neurons CANCAN generate action potentials, Glial cells generate action potentials, Glial cells

CANNOTCANNOT. however, Glia do have a resting potential.. however, Glia do have a resting potential.

3. Neurons3. Neurons HAVEHAVE synapses that use neurotransmitters. synapses that use neurotransmitters.

Glial cells Glial cells DO NOTDO NOT have chemical synapses.have chemical synapses.

4. Neurons 4. Neurons DODO NOTNOT continue to divide. Glial cellscontinue to divide. Glial cells DODO

continue to divide. continue to divide.

Glia are different from neurons:Glia are different from neurons:

Importance of glial cells in nervous system Importance of glial cells in nervous system function is VASTLY underestimated!function is VASTLY underestimated!

Evidence is mounting: Evidence is mounting: 1.1. Nurturing roleNurturing role

2.2. Signaling role (Memory?)Signaling role (Memory?)

3.3. InflammationInflammation

4.4. PainPain

5.5. Many more to come!Many more to come!

There are two main kinds in PNS

Schwann cellsSchwann cells （雪旺细胞）（雪旺细胞）

Satellite cellsSatellite cells （卫星细胞）（卫星细胞）

Schwann cell

The Schwann cell making the myelin sheath (M) around the axon (A) was cut at the level of the nucleus (N). E - endoneurium. Scale = 300 nm. (Rat, trigeminal nerve.)

Schwann 细胞功能：

形成周围神经系统的有髓神经纤维的髓鞘形成周围神经系统的有髓神经纤维的髓鞘 合成和分泌多种营养因子、细胞外基质成分和合成和分泌多种营养因子、细胞外基质成分和

细胞黏附分子。细胞黏附分子。 周围神经损伤后的再生和修复周围神经损伤后的再生和修复

Satellite cells

There are four main kinds in CNS

AstrocytesAstrocytes(( 星形胶质细胞）星形胶质细胞）OligodendrocytesOligodendrocytes(( 少突胶质细胞）少突胶质细胞）Ependymal cellsEpendymal cells (( 室管膜细胞）室管膜细胞）Microglial cellsMicroglial cells (( 小胶质细胞）小胶质细胞）

Astrocytes (AS, 星形胶质细胞）

Most numerous cell type in brainMost numerous cell type in brainConstitute ~30-50% of brain volumeConstitute ~30-50% of brain volume

Some astrocytes develop processes with Some astrocytes develop processes with expanded expanded end-feetend-feet （终足）（终足） that are linked to that are linked to endothelial cells, or to ependymal cellsendothelial cells, or to ependymal cells ，， et al.et al.

Express GFAP-an intermediate filament protein Express GFAP-an intermediate filament protein

Properties of glial cells

突起的形态的不同突起的形态的不同：： 纤维性星形细胞：纤维性星形细胞：白质中，突起细长，分支少。白质中，突起细长，分支少。 原浆性星形细胞：原浆性星形细胞：灰质中，突起粗短，分支多。灰质中，突起粗短，分支多。

抗原标记物的不同：抗原标记物的不同： 11 型星形胶质细胞：型星形胶质细胞： GFAPGFAP++/A2B5/A2B5--

22 型星形胶质细胞：型星形胶质细胞： GFAPGFAP++/A2B5/A2B5++

分 类分 类

Fibrous astrocyte

protoplasmic astrocyte

星形细胞的功能： 为神经细胞提供支持、隔离的作用为神经细胞提供支持、隔离的作用 合成和分泌多种细胞因子（黏连蛋白，生长因子和营养合成和分泌多种细胞因子（黏连蛋白，生长因子和营养

因子），参与神经损伤后再生和修复；参与神经元的迁因子），参与神经损伤后再生和修复；参与神经元的迁移；移；

参与参与血脑屏障血脑屏障的构成的构成

参与参与内环境的稳定内环境的稳定：具有多数神经递质的受体，参与神：具有多数神经递质的受体，参与神

经元及其突触功能的离子、递质和代谢的调节经元及其突触功能的离子、递质和代谢的调节 ,, 突触的突触的形成和可塑性形成和可塑性

功能：新的观点： 星形胶质细胞负责大脑信息传送星形胶质细胞负责大脑信息传送 20072007 《《 sciencescience 》》“大脑中与记忆和学习有关的海马区“大脑中与记忆和学习有关的海马区

中的星形胶质细胞能够释放一种谷氨酸化学信号，这中的星形胶质细胞能够释放一种谷氨酸化学信号，这种信号可以提高神经元间的信号效率”种信号可以提高神经元间的信号效率”

※ ※ 星形胶质细胞可以让高度兴奋的神经元保持适当星形胶质细胞可以让高度兴奋的神经元保持适当

“ “ 冷 静”，免受疾病侵袭；冷 静”，免受疾病侵袭；

※ ※ 星形胶质细胞能使神经元产生长时间增强反应，使星形胶质细胞能使神经元产生长时间增强反应，使

人学得进、记得牢。人学得进、记得牢。

星形胶质细胞与脑组织的神经干细胞密切相关星形胶质细胞与脑组织的神经干细胞密切相关

肌萎肌萎缩侧缩侧索硬索硬化症化症(AL(ALS)S)

《《 naturenature 》》美国的两个科研小组报告说美国的两个科研小组报告说 :: 一种一种名为“神经胶质细胞”的变异神经细胞所分泌的名为“神经胶质细胞”的变异神经细胞所分泌的毒素，可导致肌萎缩侧索硬化症毒素，可导致肌萎缩侧索硬化症 (ALS).(ALS).

血

脑

屏

障

Blood

brain b

arrier

end-feet that are linked to endothelial cellsend-feet that are linked to endothelial cells

内皮细胞内皮细胞 基膜基膜 星形胶质细胞星形胶质细胞

BBBBBB

1. Presence of tight junctions between the

endothelial cells

2. One of the notable features of endothelial cells

in comparison to other cell is the lack of

pinocytic vesicles( 胞饮小泡 )

3. Selective permeability to molecules based on

their molecular weight and lipid solubility

Properties of Blood Brain BarriersProperties of Blood Brain Barriers

end-feet end-feet that are that are linked to linked to endothelial endothelial cells, or to cells, or to ependymal ependymal cells, or to cells, or to the pia the pia mattermatter

Astrocytes can absorb local excess of Astrocytes can absorb local excess of neurotransmitters, and release metabolic neurotransmitters, and release metabolic and neuroactive molecules. and neuroactive molecules.

Astrocytes can influence neuronal survival Astrocytes can influence neuronal survival and activity through their ability to and activity through their ability to regulate constituents of the extracellular regulate constituents of the extracellular environmentenvironment 。。

ASAS 参与维持中枢神经系统内环境稳参与维持中枢神经系统内环境稳定定

葡萄糖葡萄糖乳糖

酵解

normal disease

储存糖原

1. 参与葡萄糖代谢参与葡萄糖代谢

2. 参与脑内谷氨酸的代谢

Nature 411, 261 - 268 (2001)

AChBP as anAChR decoy

星形胶质细胞对突触的调节作用

Astrocytes

Astrocytes contact virtually every cell Astrocytes contact virtually every cell component in braincomponent in brain

Other astrocytes (gap junctions)Other astrocytes (gap junctions) Ependymal cellsEpendymal cells Neurons (somas, processes, synapses)Neurons (somas, processes, synapses) OligodendrogliaOligodendroglia Capillary endothelial cellsCapillary endothelial cells

神经系统疾病的关系 帕金森病和帕金森病和 HuntingtonHuntington 舞蹈病：舞蹈病：运动运动

障碍性疾病，与星形胶质细胞 产生的某些物质障碍性疾病，与星形胶质细胞 产生的某些物质有关。有关。

AlzheimerAlzheimer 病：病：与细胞中产生过多的淀粉与细胞中产生过多的淀粉样前体蛋白有关。样前体蛋白有关。

Oligodendrocytes ( 少突胶质细胞）

束间少突胶质细胞 血管周少突胶质细胞 神经元周少突胶质细胞

镀银染色发现突起很少； 通过特异性的 GC 单抗做免疫细胞化学标记，

则可见少突细胞有很多突起，而且分支很多。

根据在中枢神经系统中的位置和分布：

功 能 形成中枢神经系统的形成中枢神经系统的髓鞘髓鞘

抑制神经元轴突的生长和再生抑制神经元轴突的生长和再生

（（神经突起生长抑制蛋白神经突起生长抑制蛋白））

摄取神经递质，参与神经系统内的吞噬摄取神经递质，参与神经系统内的吞噬

活动等活动等

Ependymal cells ( 室管膜细胞）

Ependymal cells

Who are the stem cells of the adult brain?astrocytes vs. ependymal cells

astrocytes

Ependymal cells

Johansson et al., "Identification of a neural stem cell in the adult mammalian central nervous system," Cell, 96:25-34, 1999. Doetsch et al., "Subventricular zone astrocytes are neural stem cells in the adult mammalian brain," Cell, 97:703-16, 1999.

The subventricular zone

Dr Jonas Frisen contends that neural stem cells are cells that line ventricles

Dr Arturo Alvarez-Buylla contends neural stem are astrocytes that lie one layer in from ventricle lining;

Microglial cells ( 小胶质细胞）

microglia

Typical features of neuronophagia, a cluster of microglia around a necrotic neuron, are shown (HE, high power).

On the left side of the diagram, cells labeled "B1", "B2", and "B3" represent chronically activated microglial cells. "B3" is a markedly elongated cell, the nucleus in particular having a long, rod-shaped form. This rod cell is classically seen in general paresis (paretic neurosyphilis) but may also be seen in other chronic disease states of the brain.

Microglial activation

"Al" is a normal resting microglial cell. Under the stimulus of tissue necrosis, the resting microglial cell undergoes hypertrophy and hyperplasia, entering an intermediate phase often referred to as the "pleomorphic microglial response". Transitional forms in this pleomorphic microglial stage would include "A2a" and "A2b". It is important to remember that as soon as the resting microglial cell is activated it becomes an active mobile scavenger cell. If the necrosis is subtotal, the microglial cells may not be stimulated to evolve beyond this "pleomorphic" stage of response. If necrosis is complete, microglia proceed through further transitional forms, as shown on the diagram, to become rounded macrophages, "A6". The latter are also referred to as "compound granular corpuscles" or "gitter cells".

功 能 吞噬功能吞噬功能 静止态静止态————反应态小胶质细胞反应态小胶质细胞

免疫功能免疫功能 神经元变性神经元变性————小胶质细胞小胶质细胞————表达表达

MHCMHC 抗原抗原————呈递给呈递给 TT 淋巴细胞淋巴细胞————

发挥免疫作用发挥免疫作用

Thanks ！