nervous tissue2k1
TRANSCRIPT
Histology of the Nervous System
Nervous Tissue
Histology of the Nervous System
Nervous Tissue
TJ del Mundo, MD, DPBOTJ del Mundo, MD, DPBO
environmentenvironment
animalanimalorganismorganism
animalanimalorganismorganism
Nervous systemNervous system
sensory sensory neuronneuron
stimulusstimulus reactionreaction
effectoreffectorInter-Inter-
neuronneuronreceptorreceptorMotorMotor
neuronneuron
Nervous System Nervous System stimulus and reaction stimulus and reaction Nervous System Nervous System stimulus and reaction stimulus and reaction
Nervous SystemNervous SystemNervous SystemNervous System
• Central Nervous SystemCentral Nervous System brain, spinal cord: brain, spinal cord: nervous tissuenervous tissue meninges, choroid plexus: meninges, choroid plexus: connective tissueconnective tissue
• Peripheral Nervous SystemPeripheral Nervous System nerve, ganglion, nerve plexusnerve, ganglion, nerve plexus:: nervous tissuenervous tissue and and connective tissueconnective tissue
cf.cf. SomaticSomatic vs vs AutonomicAutonomic Nervous System Nervous System Enteric Nervous SystemEnteric Nervous System
Nervous TissueNervous TissueNervous TissueNervous Tissue
Cellular ElementsCellular Elements
- - Neuron (Nerve Cell)Neuron (Nerve Cell)
- Neuroglial Cells- Neuroglial Cells central neurgliacentral neurglia
astrocyte, oligodendrocyte, microglia andastrocyte, oligodendrocyte, microglia and ependymal cellependymal cell
peripheral neurogliaperipheral neuroglia Schwann cell Schwann cell in nerve and ganglionin nerve and ganglion satellite (capsular) cell satellite (capsular) cell in ganglionin ganglion
Intercellular SubstanceIntercellular Substance: extremly scarse: extremly scarse
NeuronNeuronNeuronNeuron
Neuronal MorphologyNeuronal Morphology
Neuronal Cell Body (Soma)Neuronal Cell Body (Soma)
- Nucleus - Nucleus - - PerikaryonPerikaryon
Neuronal ProcessesNeuronal Processes
AxonAxon DendritesDendrites
cf. Diversity of Neuronal Size and Morphologycf. Diversity of Neuronal Size and Morphology
Diversity ofDiversity of
NeuronalNeuronal
MorphologyMorphology
1. nucleus1. nucleus
2. perikaryon 2. perikaryon
3. cell body3. cell body
4. axon4. axon
5. dendrite5. dendrite
6. Nissl body6. Nissl body
7. axon hillock7. axon hillock
8. myelin sheath8. myelin sheath
9. oligodendrocyte9. oligodendrocyte
10. Schwann cell10. Schwann cell
11. skeletal muscle cell11. skeletal muscle cell
12. neuromuscular junction12. neuromuscular junction
Morphology of
Typical Motor Neuron
Morphology of
Typical Motor Neuron
NeuronNeuronNeuronNeuron
Neuronal FunctionNeuronal Function
CommunicationCommunication
Receptor - Neuron - Effector Receptor - Neuron - Effector - - Excitability (Irritability)Excitability (Irritability) - - ConductivityConductivity through membrane through membrane in intraneuronal conductionin intraneuronal conduction
via via synapsesynapse in in interneuronal conductioninterneuronal conduction neurotransmittersneurotransmitters
Neuronal Cell Body (Soma)Neuronal Cell Body (Soma)Neuronal Cell Body (Soma)Neuronal Cell Body (Soma)
NUCLEUSNUCLEUS
ŸŸ Chromatin Pattern: Chromatin Pattern: EuchromaticEuchromatic euchromatin >>> heterochromatineuchromatin >>> heterochromatin
active active mRNAmRNA transcription transcription
cf. Barr bodycf. Barr body (facultative heterochromatin)(facultative heterochromatin)
inactive inactive X chromosomeX chromosome in female in female
ŸŸ Conspicuous NucleolusConspicuous Nucleolus NOR (nucleolar organizing region)NOR (nucleolar organizing region)
activeactive rRNArRNA transcription -- ribosometranscription -- ribosome
NB: neuronal cell bodyNB: neuronal cell body NS: Nissl substanceNS: Nissl substance
NL: nucleolusNL: nucleolus BB: Barr bodyBB: Barr body
MurrayLlewellyn
Barr 1908-1995
MurrayLlewellyn
Barr 1908-1995
Neuronal Cell Body (Soma)Neuronal Cell Body (Soma)Neuronal Cell Body (Soma)Neuronal Cell Body (Soma)
Cytoplasmic OrganellesCytoplasmic Organelles
ŸŸ Nissl substance: Nissl substance: rERrER abundant, parallally arranged rER cisternaabundant, parallally arranged rER cisterna
active site of active site of protein (polypeptide)protein (polypeptide) synthesis synthesis
- - transport vesicletransport vesicle
ŸŸ Golgi complexGolgi complex complex of perinuclear Golgi substancecomplex of perinuclear Golgi substance glycosylation, sulfation & phosphorylationglycosylation, sulfation & phosphorylation
packing and condensation protein to transportpacking and condensation protein to transport
Camilio Golgi
(1843-1926)
Golgi apparatus
Golgi method
(Golgi’s metallic impregnation)
Golgi type I & II cell
Golgi tendon organ
Golgi-Mazzoni corpuscle
Camilio Golgi
(1843-1926)
Golgi apparatus
Golgi method
(Golgi’s metallic impregnation)
Golgi type I & II cell
Golgi tendon organ
Golgi-Mazzoni corpuscle
Neuronal Cell Body (Soma)Neuronal Cell Body (Soma)Neuronal Cell Body (Soma)Neuronal Cell Body (Soma)
Protein Synthesizing AssemblyProtein Synthesizing Assembly
ŸŸ Euchromatic NucleusEuchromatic Nucleus ------- mRNA transcription------- mRNA transcription
ŸŸ Prominent NucleolusProminent Nucleolus ------- rRNA (ribosome) synthesis------- rRNA (ribosome) synthesis
ŸŸ Nissl substance:Nissl substance: rERrER ------- polypeptide chain------- polypeptide chain
ŸŸ Golgi complexGolgi complex ----- ----- destined to transportdestined to transport
-- no protein synthesizing assembly in axonno protein synthesizing assembly in axon - neurotransmitters, enzymes, membrane proteins- neurotransmitters, enzymes, membrane proteins - transport via axonal (axoplasmic) transport- transport via axonal (axoplasmic) transport
Neuronal Cell Body (Soma)Neuronal Cell Body (Soma)Neuronal Cell Body (Soma)Neuronal Cell Body (Soma)
Other Cytoplasmic OrganellesOther Cytoplasmic Organelles
ŸŸ Mitochondria Mitochondria - - energy source for energy source for ion exchangeion exchange (Na (Na++-K-K++ exchange pump) exchange pump) and and axonal transportaxonal transport
ŸŸ LysosomeLysosome - hydrolytic enzymes --- waste products- hydrolytic enzymes --- waste products - lysosomal storage disease (mental retardation, seizure)- lysosomal storage disease (mental retardation, seizure)
Pigment GranulesPigment Granules
Lipofuscin granuleLipofuscin granule, , Melanin granuleMelanin granule
PigmentsPigmentsPigmentsPigments
lipofuscinlipofuscinmelaninmelanin
Neuronal Cell Body (Soma)Neuronal Cell Body (Soma)Neuronal Cell Body (Soma)Neuronal Cell Body (Soma)
Neuronal Cell Body (Soma)Neuronal Cell Body (Soma)Neuronal Cell Body (Soma)Neuronal Cell Body (Soma)
CytoskeletonCytoskeleton
ŸŸ Neurofilament: Intermediate Filament Neurofilament: Intermediate Filament - supporting- supporting
- neurofibril -------- neurofibril ------- reduced silver stainingreduced silver staining
Fink-Heimer methodFink-Heimer method
ŸŸ MicrotubuleMicrotubule - tubulin- tubulin - fast anterograde axonal transport and- fast anterograde axonal transport and retrograde axonal transportretrograde axonal transport
cf. microfilament:cf. microfilament: actin, postsynaptic membraneactin, postsynaptic membrane
CytoskeletonCytoskeleton
NeurofilamentNeurofilament
MicrotubuleMicrotubule
Neurofibril - Neurofibril - neurofilamentneurofilament
Distinction between Axon and DendritesDistinction between Axon and DendritesDistinction between Axon and DendritesDistinction between Axon and Dendrites
Axon Axon Dendrite Dendrite
DimensionDimensionnumbernumber 11 multiple (0, 1, or more)multiple (0, 1, or more)lengthlength 200 200 m – 1 mm – 1 m less than 700 less than 700 m mdiameterdiameter constant throughoutconstant throughout gradually tapered gradually tapered
Branching patternBranching patternangleangle almost right anglealmost right angle acute angle acute anglesitesite distant from cell bodydistant from cell body near cell body near cell body
Structural componentsStructural componentsNissl substanceNissl substance absentabsent could be present could be presentdendritic spinedendritic spine absentabsent could be present could be presentmyelin sheathmyelin sheath could be associatedcould be associated not associated not associated
DendriteDendrite
NisslNissl
dendritic spinedendritic spine
Distinction between Axon and DendritesDistinction between Axon and DendritesDistinction between Axon and DendritesDistinction between Axon and Dendrites
Axon Axon Dendrite Dendrite
Staining propertyStaining property GolgiGolgi hard to impregnatehard to impregnate well delineated well delineated impregnation impregnation (except rapid Golgi method)(except rapid Golgi method)
reduced silverreduced silver more darkly stainedmore darkly stained less darkly stained less darkly stained
FunctionalFunctional direction ofdirection of efferent efferent afferent afferent conductionconduction (soma (soma → axon terminal) (dendrite → soma)→ axon terminal) (dendrite → soma)
exception: pseudounipolar neuronexception: pseudounipolar neuron
Golgi methodGolgi method
Reduced silver methodReduced silver method
SYNAPSESYNAPSESYNAPSESYNAPSE
ŸŸ Presynaptic Portion: Synaptic Button Presynaptic Portion: Synaptic Button - synaptic vesicle- synaptic vesicle
- mitochondria- mitochondria - presynaptic membrane: tubulin- presynaptic membrane: tubulin
ŸŸ Synaptic Cleft Synaptic Cleft - 20-30 nm- 20-30 nm
ŸŸ Postsynaptic PortionPostsynaptic Portion - postsynaptic membrane: actin, fodrin, spectrin- postsynaptic membrane: actin, fodrin, spectrin
- mitochondria- mitochondria
SYNAPSESYNAPSESYNAPSESYNAPSE
SYNAPSESYNAPSE
Components of Axonal (Axoplasmic) TransportComponents of Axonal (Axoplasmic) Transport
Components Velocity (mm/day) Transporting SubstancesComponents Velocity (mm/day) Transporting Substances
Anterograde Axonal TransportAnterograde Axonal Transport Fast Transport Fast Transport 200-400200-400 synaptic vesicle, enzymes neurotransmitters Mitochondrial Transport 50-10050-100 mitochondria
Slow TransportSlow Transport
Slow Components a (SCa) 0.1 - 1.00.1 - 1.0 tubulin, neurofilament protein Slow Comnponent b (SCb) 2 - 62 - 6 actin, clathrine, calmodulins spectrin, cytoplasmic enzymes Retrograde Axonal Transport Retrograde Axonal Transport 100-200100-200 prelysosomal vesicles, recycled proteins, HRP, WGA neurotrophic viruses
Axonal (Axoplasmic) TransportAxonal (Axoplasmic) TransportAxonal (Axoplasmic) TransportAxonal (Axoplasmic) Transport
Mechanism ofMechanism of Axonal Axonal TransportTransport
FastFast AnterogradeAnterograde Axonal transportAxonal transport
andand
RetrogradeRetrograde Axonal transportAxonal transport
Mechanism ofMechanism of Axonal Axonal TransportTransport
FastFast AnterogradeAnterograde Axonal transportAxonal transport
andand
RetrogradeRetrograde Axonal transportAxonal transport
Degeneration and RegenerationDegeneration and Regenerationof Nervous Systemof Nervous System
Degeneration and RegenerationDegeneration and Regenerationof Nervous Systemof Nervous System
1. Wallerian Degeneration1. Wallerian Degeneration - changes distal to the injury site- changes distal to the injury site - myelin breakdown- myelin breakdown - von B- von Büüngnerngner’’s band - Schwann cells band - Schwann cell - neuroma formation- neuroma formation
2. Axon Reaction (Chromatolysis, 2. Axon Reaction (Chromatolysis, Nissl Reaction)Nissl Reaction) - displacement of nucleus- displacement of nucleus - chromatolysis- chromatolysis - regenerative processes- regenerative processes
Augustus Waller (1816-1870) Augustus Waller (1816-1870)
Wallerian degenerationWallerian degeneration
Axon (Nissl) Reaction - chromatolysis Axon (Nissl) Reaction - chromatolysis Axon (Nissl) Reaction - chromatolysis Axon (Nissl) Reaction - chromatolysis
Tract Tracing MethodsTract Tracing MethodsTract Tracing MethodsTract Tracing Methods
1) retrograde tracing methods1) retrograde tracing methods
axon, axon terminal axon, axon terminal cell body cell body
2) anterograde tracing methods2) anterograde tracing methods
cell body cell body axon, axon terminal axon, axon terminal
cell body ---- axon terminalcell body ---- axon terminal
based on based on nerve degenerationnerve degeneration and and axonal transportaxonal transport
1. Nissl Reaction1. Nissl Reaction
methylene blue, toluidine blue,methylene blue, toluidine blue,
thionin, cresyl violetthionin, cresyl violet
2. Retrograde Tracer2. Retrograde Tracer
Horseradish Peroxidase (HRP)Horseradish Peroxidase (HRP)
Wheat-germ Agglutinin (WGA) Wheat-germ Agglutinin (WGA)
Fluorescence TracerFluorescence Tracer
- Lucifer Yellow, Fast Blue, Nuclear Yellow- Lucifer Yellow, Fast Blue, Nuclear Yellow
Viruses and ToxoidsViruses and Toxoids
Retrograde Tracing MethodsRetrograde Tracing MethodsRetrograde Tracing MethodsRetrograde Tracing Methods
Retrograde Labeling of HRPRetrograde Labeling of HRP Retrograde Labeling of HRPRetrograde Labeling of HRP
1. Marchi Method1. Marchi Method OsO4 after tract of nerve lesionOsO4 after tract of nerve lesion
2. Nauta Method - Fink Heimer method2. Nauta Method - Fink Heimer method
Reduced Silver Method after tract lesionReduced Silver Method after tract lesion
3. Autoradiograhy with Radiolabelled Amino Acid3. Autoradiograhy with Radiolabelled Amino Acid
Tritiated Glycine Tritiated Glycine
4. Anterograde Tracer4. Anterograde Tracer
Phageolus Vulgaris Leucoagglutinin (PHA-L)Phageolus Vulgaris Leucoagglutinin (PHA-L)
Anterograde Tracing MethodsAnterograde Tracing MethodsAnterograde Tracing MethodsAnterograde Tracing Methods
Marchi method - Wallerian degeneration Marchi method - Wallerian degeneration Marchi method - Wallerian degeneration Marchi method - Wallerian degeneration
Nauta methodNauta method
Reduced silver methodReduced silver method
after axon transectionafter axon transection
neurofilamentneurofilament transport transport
continues after axoncontinues after axon
transectiontransection
Nauta-GygaxNauta-Gygax method method
Fink-HeimerFink-Heimer method method
33H-labeled amino acidH-labeled amino acid
AutoradiographyAutoradiography
Amino acid is incorporatedAmino acid is incorporated
to protein in neuronal to protein in neuronal
cell bodies cell bodies
Proteins are slowly Proteins are slowly
transported to axonaltransported to axonal
endingsendings
Classification of NeuronsClassification of NeuronsClassification of NeuronsClassification of Neurons
(1) by the Number of Processes(1) by the Number of Processes 1. unipolar neuron1. unipolar neuron 2. pseudounipolar neuron2. pseudounipolar neuron 3. bipolar neuron3. bipolar neuron 4. multipolar neuron4. multipolar neuron
(2) by the Length of Axon(2) by the Length of Axon 1. Golgi type I neuron1. Golgi type I neuron 2. Golgi type II neuron2. Golgi type II neuron
(3) by the Morphology of Dendrites(3) by the Morphology of Dendrites (Topognostic Value)(Topognostic Value) 1. isodendritic neuron1. isodendritic neuron 2. allodendritic neuron2. allodendritic neuron 3. idiodendritic neuron3. idiodendritic neuron
1. unipolar neuron 2. bipolar neuron
3. pseudounipolar neuron 4. multipolar neuron
a. axon d. dendrite
1. unipolar neuron 2. bipolar neuron
3. pseudounipolar neuron 4. multipolar neuron
a. axon d. dendrite
Pseudounipolar NeuronPseudounipolar Neuron
DRG (dorsal root ganglion) neuronDRG (dorsal root ganglion) neuron
pseudounipolar cellpseudounipolar cell
peripheralperipheralprocessprocess
centralcentralprocessprocess
telodendrontelodendrontelodendrontelodendron
cell body cell body in DRGin DRG
Neuroglia (Neuroglial Cells)Neuroglia (Neuroglial Cells)Neuroglia (Neuroglial Cells)Neuroglia (Neuroglial Cells)
Central NeurogliaCentral Neuroglia AstrocyteAstrocyte protoplasmic astrocyteprotoplasmic astrocyte fibrous astrocytefibrous astrocyte
OligodendrocyteOligodendrocyte perineuronal satellite cellperineuronal satellite cell interfascicular cellinterfascicular cell
MicrogliaMicroglia Ependymal CellEpendymal Cell
Peripheral NeurogliaPeripheral Neuroglia Schwann CellSchwann Cell
in peripheral nervein peripheral nerve
and ganglionand ganglion
Capsular (Satellite) CellCapsular (Satellite) Cell
in ganglionin ganglion
AstrocyteAstrocyte Oligodendrocyte Oligodendrocyte Microglia Microglia
Central NeurogliaCentral NeurogliaCentral NeurogliaCentral Neuroglia
AstrocyteAstrocyteAstrocyteAstrocyte
• Protoplasmic Astrocyte: Gray Matter Protoplasmic Astrocyte: Gray Matter • Fibrous Astrocyte: White MatterFibrous Astrocyte: White Matter
Cell BodyCell Body ‘‘potatopotato’’ shape nucleus, scarse pale cytopasm shape nucleus, scarse pale cytopasm
ProcessesProcesses - - GFAP GFAP (glial fibroacidic protein):(glial fibroacidic protein): intermediate filament intermediate filament
-- Perivascular Feet Perivascular Feet (Foot Process, Vascular End-Feet)(Foot Process, Vascular End-Feet) surrounding blood vesselssurrounding blood vessels
Specialized AstrocytesSpecialized Astrocytes
- Bergmann- Bergmann’’s gial cell, Muller cell, pituicytes gial cell, Muller cell, pituicyte
ProtoplasmicProtoplasmic Fibrous Fibrous Synaptic Synaptic
AstrocyteAstrocyte AstrocyteAstrocyte Glomerulus Glomerulus
OligodendrocyteOligodendrocyteOligodendrocyteOligodendrocyte
• Perineuronal Satellite Cell Perineuronal Satellite Cell • Interfascicular CellInterfascicular Cell
Cell BodyCell Body round, heterochromatic nucleusround, heterochromatic nucleus dark cytopasmdark cytopasm - rER, free ribosome, Golgi complex, mitochondria- rER, free ribosome, Golgi complex, mitochondria
Myelin forming cell in CNSMyelin forming cell in CNS - - Myelin SheathMyelin Sheath
Each process constitutes a Each process constitutes a internodal segmentinternodal segment
Oligodendrocyte
1. nucleus of
oligodendrocyte
2. process of
oligodendrocyte
3. myelin sheath
4. axon
Oligodendrocyte
1. nucleus of
oligodendrocyte
2. process of
oligodendrocyte
3. myelin sheath
4. axon
MicrogliaMicrogliaMicrogliaMicroglia
Cell BodyCell Body slender, indented, heterochromatic nucleusslender, indented, heterochromatic nucleus dark cytopasmdark cytopasm - prominent secondary lysosome- prominent secondary lysosome
ProcessesProcessesshort, highly branchedshort, highly branched
Macrophage (Mononuclear Phagocytic) SystemMacrophage (Mononuclear Phagocytic) SystemMesenchymal Origin - Blood MonocyteMesenchymal Origin - Blood MonocyteIncreased inIncreased in Inflammation Inflammation
Microglia
1. nucleus of
microglia
2. process of
microglia
3. lysosome
4. capillary
5. pericyte
Microglia
1. nucleus of
microglia
2. process of
microglia
3. lysosome
4. capillary
5. pericyte
Ependymal CellEpendymal CellEpendymal CellEpendymal Cell
Epithelial Cell Epithelial Cell lining ventricular surfacelining ventricular surface cilia and microvilli on luminal surfacecilia and microvilli on luminal surface simple cuboidal cell with round nucleussimple cuboidal cell with round nucleus
TanicyteTanicytebasal process, numerous in 3rd ventriclebasal process, numerous in 3rd ventriclemost ependymal cell has basal processmost ependymal cell has basal process (Chung & Lee, 1988)(Chung & Lee, 1988)
Choroid Plexus Epithelial CellsChoroid Plexus Epithelial Cellsion transporting cell: numerous mitochondriaion transporting cell: numerous mitochondria
Schwann CellSchwann CellSchwann CellSchwann Cell
Slender Cell Slender Cell with small heterochromatic nucleiwith small heterochromatic nuclei
Myelin forming cell in PNSMyelin forming cell in PNS - - Myelin Sheath: Myelin Sheath: Myelinated FiberMyelinated Fiber
A Schwann cell constitutes a internodal SegmentA Schwann cell constitutes a internodal Segment
Surround Surround Unmyelinated AxonsUnmyelinated Axons A schwann cell surround A schwann cell surround
many unmyelinated axonsmany unmyelinated axons
Schwann CellSchwann Cell
Satellite (Capsular) CellSatellite (Capsular) CellSatellite (Capsular) CellSatellite (Capsular) Cell
Squamous Cell encircles Squamous Cell encircles neuronal cell bodyneuronal cell body
in Ganglion in Ganglion
- completely encircles pseudounipolar neuron- completely encircles pseudounipolar neuron
in in spinal and cranial ganglionspinal and cranial ganglion
- neurons of autonomic ganglia were - neurons of autonomic ganglia were
less completely surrounded by satellite cellless completely surrounded by satellite cell
Myelin Sheath - MYELINMyelin Sheath - MYELIN cf. Schwann sheath, Neurilemmacf. Schwann sheath, Neurilemma
• formed by wrapped plasma membrane offormed by wrapped plasma membrane of OligodendrocyteOligodendrocyte in CNS in CNS Schwann CellSchwann Cell in PNS in PNS
• Node of RanvierNode of Ranvier - Saltatory Conduction - Saltatory Conduction evolutionary innovation in chordateevolutionary innovation in chordate - - conduction velocityconduction velocity
MyelinMyelinMyelinMyelin
MyelinMyelinMyelinMyelin
Node of Ranvier - Internodal segmentNode of Ranvier - Internodal segmentSchmidt-LantermannSchmidt-Lantermann’’s clefts cleft
Osmium tetroxide (OsOOsmium tetroxide (OsO44)) stain for Myelinstain for Myelin
MyelinMyelin
Structure of fast nerve conductionStructure of fast nerve conduction
Giant squid axon 0.5-1 mm in diameterGiant squid axon 0.5-1 mm in diameter
conduction velocity 25 m/sconduction velocity 25 m/s
MyelinMyelinMyelinMyelin
Conduction velocityConduction velocity is proportional to is proportional to
1. The Length of Internodal Segment1. The Length of Internodal Segment
2. Thickness of Myelin2. Thickness of Myelin
3. Diameter of Nerve Fiber3. Diameter of Nerve Fiber
Conduction velocity of Conduction velocity of
mammalian nerve fibermammalian nerve fiber
Group IGroup I AA 10 - 20 10 - 20 70 -120 70 -120
Group IIGroup II AA 5 - 12 5 - 12 30 - 70 30 - 70
AAγγ 3 - 6 3 - 6 15 - 30 15 - 30
Group IIIGroup III AAδδ 2 - 5 2 - 5 12 - 30 12 - 30
BB < 3 < 3 3 - 15 3 - 15
Group IVGroup IV CC 0.1 - 1.5 0.1 - 1.5 0.5 - 20.5 - 2
Myelinated fiberMyelinated fiber
Unmyelinated fiberUnmyelinated fiber
Myelin FormationMyelin FormationMyelin FormationMyelin Formation
MyelinMyelinMyelinMyelin
MyelinMyelinformationformation
Schwann cellSchwann celloligodendrocyteoligodendrocyte
MYELIN - Fusion of Plasma MembraneMYELIN - Fusion of Plasma Membrane Major Dense LineMajor Dense Line - fusion of inner leaflet - fusion of inner leaflet ---- Myelin Basic Protein (MBP)---- Myelin Basic Protein (MBP)
Intraperiod LineIntraperiod Line - fusion of outer leaflet - fusion of outer leaflet ---- Proteolipid Protein (PLP)---- Proteolipid Protein (PLP)
in oligodendrocytein oligodendrocyte ---- Protein Zero (P---- Protein Zero (P00) )
in Schwann Cellin Schwann Cell
MyelinMyelinMyelinMyelin
MyelinMyelinMyelinMyelin
1. trilaminar unit membrane1. trilaminar unit membrane 2. major dense line 2. major dense line
3. intraperiod line3. intraperiod line 4. Cytoplasm of Schwann cell 4. Cytoplasm of Schwann cell
Multiple Slerosis Multiple Slerosis – disease of the myelin– disease of the myelin
Jacqueline Du PreJacqueline Du PreJacqueline Du PreJacqueline Du Preoligodendrocyteoligodendrocyte
LEPROSY:LEPROSY: Mycobactrium lepraeMycobactrium leprae infection ofinfection of Schwann cellSchwann cell
Rembrandt. Rembrandt. The King Uzziah Stricken with Leprosy. The King Uzziah Stricken with Leprosy.
Organization of Nervous SystemOrganization of Nervous SystemOrganization of Nervous SystemOrganization of Nervous System
Central Nervous SystemCentral Nervous System
Gray MatterGray Matter Nucleus and CortexNucleus and Cortex White MatterWhite Matter TractsTracts
Peripheral Nervous SystemPeripheral Nervous System
Nerve (Peripheral Nerve)Nerve (Peripheral Nerve) GanglionGanglion
Peripheral NervePeripheral Nerve
Nerve FiberNerve Fiber
Myelinated Nerve Fiber Myelinated Nerve Fiber
Axon,Axon, Myelin sheathMyelin sheath, Schwann cell, Schwann cell
Unmyelinated Nerve Fiber Unmyelinated Nerve Fiber Axon, Schwann cellAxon, Schwann cell
Connective Tissue SheathConnective Tissue Sheath
EndoneuriumEndoneurium Perineurium – blood vesselsPerineurium – blood vessels EpineuriumEpineurium
Composition of Peripheral NerveComposition of Peripheral NerveComposition of Peripheral NerveComposition of Peripheral Nerve
Composition of Peripheral NerveComposition of Peripheral NerveComposition of Peripheral NerveComposition of Peripheral Nerve
Peripheral Nerve Endings:Peripheral Nerve Endings:Afferent EndingsAfferent Endings
RReceptor Neurons of Craniospinal Ganglioneceptor Neurons of Craniospinal Ganglion
ŸŸpseudounipolar neurons of dorsal root gangliapseudounipolar neurons of dorsal root ganglia
ŸŸ trigeminal (semilunar, Gasserian ganglion), trigeminal (semilunar, Gasserian ganglion), geniculate (VII), superior IX, superior X ganglia (GSA)geniculate (VII), superior IX, superior X ganglia (GSA)
ŸŸgeniculate (VII), inferior IX, inferior X ganglia (VA)geniculate (VII), inferior IX, inferior X ganglia (VA)
Morphological ClassificationMorphological Classification
ŸŸ free nerve endingsfree nerve endings
ŸŸ expanded tip endings expanded tip endings
ŸŸ encapsulated endings encapsulated endings ----- CT envestment----- CT envestment
Afferent EndingsAfferent Endings
Free Nerve EndingsFree Nerve Endings
- Nerve endings without special structural- Nerve endings without special structural
organizationorganization
- - pain and temperaturepain and temperature receptor receptor
Expanded Tip EndingsExpanded Tip Endings
- - MerkelMerkel’’s Touch Corpuscles Touch CorpuscleMerkel cells in basal layer of epidermisMerkel cells in basal layer of epidermis
- - Type I Hair cellsType I Hair cells of Vestibular Labyrinth of Vestibular Labyrinth
Afferent EndingsAfferent Endings
Encapsulated EndingsEncapsulated Endings
- Meissner- Meissner’’s Corpuscles Corpuscle
- Pacinian Corpuscle- Pacinian Corpuscle
(Corpuscle of Vater-Pacini)(Corpuscle of Vater-Pacini)
- Genital Corpuscle- Genital Corpuscle
- Ruffini- Ruffini’’s Endings Ending
- End Bulb of Krause- End Bulb of Krause
- - Golgi tendon organ:Golgi tendon organ: ProprioceptorProprioceptor
Receptor Receptor
EndingsEndings
ŸŸ Free nerve Free nerve endingending
ŸŸ Expanded Expanded tip endingtip ending
ŸŸ Encapsulated Encapsulated endingending
MerkelMerkel’’s s
Touch CorpuscleTouch Corpuscle
ŸŸ expanded tip endingexpanded tip ending
ŸŸ Merkel cell Merkel cell - clear cell located in the- clear cell located in the
basal layer of epidermisbasal layer of epidermis
- membrane bound electron - membrane bound electron
dense granules resemblesdense granules resembles
synaptic vesiclesynaptic vesicle
MeissnerMeissner’’s Corpuscles Corpuscle
Pacinian CorpusclePacinian Corpuscle
Other Encapsulated EndingsOther Encapsulated Endings
End Bulb of KrauseEnd Bulb of Krause Genital Corpuscle Lingual CorpuscleGenital Corpuscle Lingual Corpuscle
Efferent EndingsEfferent Endings
Somatic Efferent EndingsSomatic Efferent Endings
Neuromuscular JunctionNeuromuscular Junction (Myoneural Junction, Motor End Plate)(Myoneural Junction, Motor End Plate)
Autonomic Efferent EndingsAutonomic Efferent Endings
Endings on smooth muscle Endings on smooth muscle
and blood vessels and blood vessels
Somatic Efferent EndingsSomatic Efferent Endings
Neuromuscular JunctionNeuromuscular Junction (Myoneural Junction, Motor End Plate)(Myoneural Junction, Motor End Plate)
Autonomic Efferent EndingsAutonomic Efferent Endings
Endings on smooth muscle Endings on smooth muscle
and blood vessels and blood vessels
NeuromuscularNeuromuscularJunctionJunction
(Myoneural Junction,(Myoneural Junction,
Motor End Plate)Motor End Plate)
NeuromuscularNeuromuscularJunctionJunction
(Myoneural Junction,(Myoneural Junction,
Motor End Plate)Motor End Plate)
NMJNMJNMJNMJ
MM
NN
Neuromuscular JunctionNeuromuscular Junction
(Motor End Plate)(Motor End Plate)Neuromuscular JunctionNeuromuscular Junction
(Motor End Plate)(Motor End Plate)
Myasthenia GravisMyasthenia GravisMyasthenia GravisMyasthenia Gravis
• muscle weaknessmuscle weakness which is greatly which is greatly increased by exertion or increased by exertion or repeated contractionrepeated contraction
• autoimmune disease autoimmune disease with autoantibodieswith autoantibodies against against Ach receptorAch receptor
• maybe fatal if untreatedmaybe fatal if untreated by respiratory paralysisby respiratory paralysis
• treated withtreated with AchT inhibitorsAchT inhibitors, , thymectomy, and thymectomy, and corticosteroidscorticosteroids
Defects in NMDefects in NM
TransmissionTransmission
before treatment after treatmentbefore treatment after treatment
Autonomic Efferent EndingsAutonomic Efferent EndingsAutonomic Efferent EndingsAutonomic Efferent Endings
Neuromuscular SpindleNeuromuscular Spindle
• Both receptor and effectorBoth receptor and effector
• StructureStructure
1. Capsule1. Capsule
2. Intrafusal Muscle Fibers2. Intrafusal Muscle Fibers
- Nuclear Bag Fiber- Nuclear Bag Fiber - Nuclear Chain Fiber- Nuclear Chain Fiber
3. Receptor and Effector Nerve Endings3. Receptor and Effector Nerve Endings
- Afferent Ending- Afferent Ending - Efferent Ending- Efferent Ending
NB: nuclear bag fiber NB: nuclear bag fiber IF: intrafusal muscle fiberIF: intrafusal muscle fiber
CA: capsule CA: capsule EF: extrafusal muscle fiberEF: extrafusal muscle fiber
Neuromuscular SpindleNeuromuscular Spindle
• INTRAFUSAL MUSCLE FIBERSINTRAFUSAL MUSCLE FIBERS
(1) Nuclear Bag Fiber(1) Nuclear Bag Fiber
- 1-4 / each spindle- 1-4 / each spindle
- longer and thicker than nuclear chain fiber- longer and thicker than nuclear chain fiber
- large central aggregation of nucleus in- large central aggregation of nucleus in
equatorial regionequatorial region
(2) Nuclear Chain Fiber(2) Nuclear Chain Fiber - many fibers / spindle- many fibers / spindle - smaller and thinner than nuclear bag fiber- smaller and thinner than nuclear bag fiber - central row of nucleus in equatorial region- central row of nucleus in equatorial region
Neuromuscular SpindleNeuromuscular Spindle
INNERVATIONINNERVATION
Afferent Fibers: ProprioceptorsAfferent Fibers: Proprioceptors
(1) Primary (Annulospiral) Endings(1) Primary (Annulospiral) Endings
- Group Ia (12-20 - Group Ia (12-20 m in diameter) afferentsm in diameter) afferents
- terminate in both NB and NC fibers- terminate in both NB and NC fibers
- wound around the central equatorial region- wound around the central equatorial region
(2) Secondary (Flower-Spray) Endings(2) Secondary (Flower-Spray) Endings - group II (6-8 - group II (6-8 m in diameter) afferentm in diameter) afferent - terminates predominantly in nuclear chain fiber- terminates predominantly in nuclear chain fiber - terminates around juxtaequatorial region- terminates around juxtaequatorial region
Neuromuscular SpindleNeuromuscular Spindle
• INNERVATIONINNERVATION
Efferent FibersEfferent Fibers
Gamma (Gamma () Motor Fiber) Motor Fiber
- terminates in small motor end plates- terminates in small motor end plates
of the non-nucleated (striated) regionof the non-nucleated (striated) region
of both intrafusal muscle fibers of both intrafusal muscle fibers