Nervous tissue2k1

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  • Nervous tissue2k1

    1. 1. Histology of the Nervous System Nervous Tissue TJ del Mundo, MD, DPBO
    2. 2. environment animal organism Nervous system sensory neuron stimulus reaction effector Inter- neuron receptor Motor neuron Nervous System stimulus and reaction
    3. 3. Nervous System <ul><li>Central Nervous System </li></ul><ul><li>brain, spinal cord: nervous tissue </li></ul><ul><li>meninges, choroid plexus: connective tissue </li></ul><ul><li>Peripheral Nervous System </li></ul><ul><li>nerve, ganglion, nerve plexus : </li></ul><ul><li>nervous tissue and connective tissue </li></ul><ul><li>cf. Somatic vs Autonomic Nervous System </li></ul><ul><li>Enteric Nervous System </li></ul>
    4. 4. Nervous Tissue Cellular Elements - Neuron (Nerve Cell) - Neuroglial Cells central neurglia astrocyte, oligodendrocyte, microglia and ependymal cell peripheral neuroglia Schwann cell in nerve and ganglion satellite (capsular) cell in ganglion Intercellular Substance : extremly scarse
    5. 5. Neuron Neuronal Morphology Neuronal Cell Body (Soma) - Nucleus - Perikaryon Neuronal Processes Axon Dendrites cf. Diversity of Neuronal Size and Morphology
    6. 7. Diversity of Neuronal Morphology
    7. 8. Morphology of Typical Motor Neuron 1. nucleus 2. perikaryon 3. cell body 4. axon 5. dendrite 6. Nissl body 7. axon hillock 8. myelin sheath 9. oligodendrocyte 10. Schwann cell 11. skeletal muscle cell 12. neuromuscular junction
    8. 9. Neuron Neuronal Function Communication Receptor - Neuron - Effector - Excitability (Irritability) - Conductivity through membrane in intraneuronal conduction via synapse in interneuronal conduction neurotransmitters
    9. 10. Neuronal Cell Body (Soma) NUCLEUS Ÿ Chromatin Pattern: Euchromatic euchromatin >>> heterochromatin active mRNA transcription cf. Barr body (facultative heterochromatin) inactive X chromosome in female Ÿ Conspicuous Nucleolus NOR (nucleolar organizing region) active rRNA transcription -- ribosome
    10. 11. NB: neuronal cell body NS: Nissl substance NL: nucleolus BB: Barr body
    11. 12. Murray Llewellyn Barr 1908-1995
    12. 14. Neuronal Cell Body (Soma) Cytoplasmic Organelles Ÿ Nissl substance: rER abundant, parallally arranged rER cisterna active site of protein (polypeptide) synthesis - transport vesicle Ÿ Golgi complex complex of perinuclear Golgi substance glycosylation, sulfation & phosphorylation packing and condensation protein to transport
    13. 17. Camilio Golgi (1843-1926) Golgi apparatus Golgi method (Golgi’s metallic impregnation) Golgi type I & II cell Golgi tendon organ Golgi-Mazzoni corpuscle
    14. 18. Neuronal Cell Body (Soma) Protein Synthesizing Assembly Ÿ Euchromatic Nucleus ------- mRNA transcription Ÿ Prominent Nucleolus ------- rRNA (ribosome) synthesis Ÿ Nissl substance: rER ------- polypeptide chain Ÿ Golgi complex ----- destined to transport - no protein synthesizing assembly in axon - neurotransmitters, enzymes, membrane proteins - transport via axonal (axoplasmic) transport
    15. 19. Neuronal Cell Body (Soma) Other Cytoplasmic Organelles Ÿ Mitochondria - energy source for ion exchange (Na + -K + exchange pump) and axonal transport Ÿ Lysosome - hydrolytic enzymes --- waste products - lysosomal storage disease (mental retardation, seizure) Pigment Granules Lipofuscin granule , Melanin granule
    16. 22. Pigments lipofuscin melanin
    17. 23. Neuronal Cell Body (Soma)
    18. 24. Neuronal Cell Body (Soma) Cytoskeleton Ÿ Neurofilament: Intermediate Filament - supporting - neurofibril ------- reduced silver staining Fink-Heimer method Ÿ Microtubule - tubulin - fast anterograde axonal transport and retrograde axonal transport  cf. microfilament: actin, postsynaptic membrane
    19. 25. Cytoskeleton Neurofilament Microtubule
    20. 26. Neurofibril - neurofilament
    21. 27. Distinction between Axon and Dendrites Axon Dendrite Dimension number 1 multiple (0, 1, or more) length 200  m – 1 m less than 700  m diameter constant throughout gradually tapered Branching pattern angle almost right angle acute angle site distant from cell body near cell body Structural components Nissl substance absent could be present dendritic spine absent could be present myelin sheath could be associated not associated
    22. 30. Dendrite Nissl
    23. 32. dendritic spine
    24. 34. Distinction between Axon and Dendrites Axon Dendrite Staining property Golgi hard to impregnate well delineated impregnation (except rapid Golgi method) reduced silver more darkly stained less darkly stained Functional direction of efferent afferent conduction (soma -> axon terminal) (dendrite -> soma) exception: pseudounipolar neuron
    25. 35. Golgi method
    26. 36. Reduced silver method
    27. 37. SYNAPSE Ÿ Presynaptic Portion: Synaptic Button - synaptic vesicle - mitochondria - presynaptic membrane: tubulin Ÿ Synaptic Cleft - 20-30 nm Ÿ Postsynaptic Portion - postsynaptic membrane: actin, fodrin, spectrin - mitochondria
    28. 38. SYNAPSE
    29. 39. SYNAPSE
    30. 40. Components of Axonal (Axoplasmic) Transport Components Velocity (mm/day) Transporting Substances Anterograde Axonal Transport Fast Transport 200-400 synaptic vesicle, enzymes neurotransmitters Mitochondrial Transport 50-100 mitochondria Slow Transport Slow Components a (SCa) 0.1 - 1.0 tubulin, neurofilament protein Slow Comnponent b (SCb) 2 - 6 actin, clathrine, calmodulins spectrin, cytoplasmic enzymes Retrograde Axonal Transport 100-200 prelysosomal vesicles, recycled proteins, HRP, WGA neurotrophic viruses Axonal (Axoplasmic) Transport
    31. 41. Mechanism of Axonal Transport Fast Anterograde Axonal transport and Retrograde Axonal transport
    32. 42. Degeneration and Regeneration of Nervous System 1. Wallerian Degeneration - changes distal to the injury site - myelin breakdown - von B ü ngner’s band - Schwann cell - neuroma formation 2. Axon Reaction (Chromatolysis, Nissl Reaction) - displacement of nucleus - chromatolysis - regenerative processes
    33. 43. Augustus Waller (1816-1870) Wallerian degeneration
    34. 44. Axon (Nissl) Reaction - chromatolysis
    35. 46. Tract Tracing Methods 1) retrograde tracing methods axon, axon terminal  cell body 2) anterograde tracing methods cell body  axon, axon terminal cell body ---- axon terminal  based on nerve degeneration and axonal transport
    36. 47. 1. Nissl Reaction methylene blue, toluidine blue, thionin, cresyl violet 2. Retrograde Tracer Horseradish Peroxidase (HRP) Wheat-germ Agglutinin (WGA) Fluorescence Tracer - Lucifer Yellow, Fast Blue, Nuclear Yellow Viruses and Toxoids Retrograde Tracing Methods
    37. 48. Retrograde Labeling of HRP
    38. 49. 1. Marchi Method OsO4 after tract of nerve lesion 2. Nauta Method - Fink Heimer method Reduced Silver Method after tract lesion 3. Autoradiograhy with Radiolabelled Amino Acid Tritiated Glycine 4. Anterograde Tracer Phageolus Vulgaris Leucoagglutinin (PHA-L) Anterograde Tracing Methods
    39. 50. Marchi method - Wallerian degeneration
    40. 51. Nauta method  Reduced silver method after axon transection  neurofilament transport continues after axon transection  Nauta-Gygax method Fink-Heimer method
    41. 52. 3 H-labeled amino acid Autoradiography  Amino acid is incorporated to protein in neuronal cell bodies  Proteins are slowly transported to axonal endings
    42. 53. Classification of Neurons (1) by the Number of Processes 1. unipolar neuron 2. pseudounipolar neuron 3. bipolar neuron 4. multipolar neuron (2) by the Length of Axon 1. Golgi type I neuron 2. Golgi type II neuron (3) by the Morphology of Dendrites (Topognostic Value) 1. isodendritic neuron 2. allodendritic neuron 3. idiodendritic neuron
    43. 54. 1. unipolar neuron 2. bipolar neuron 3. pseudounipolar neuron 4. multipolar neuron a. axon d. dendrite
    44. 55. Pseudounipolar Neuron DRG (dorsal root ganglion) neuron pseudounipolar cell peripheral process central process telodendron cell body in DRG
    45. 56. Neuroglia (Neuroglial Cells) Central Neuroglia Astrocyte protoplasmic astrocyte fibrous astrocyte Oligodendrocyte perineuronal satellite cell interfascicular cell Microglia Ependymal Cell Peripheral Neuroglia Schwann Cell in peripheral nerve and ganglion Capsular (Satellite) Cell in ganglion
    46. 57. Astrocyte Oligodendrocyte Microglia Central Neuroglia
    47. 59. Astrocyte <ul><li>Protoplasmic Astrocyte: Gray Matter </li></ul><ul><li>Fibrous Astrocyte: White Matter </li></ul><ul><li>Cell Body </li></ul><ul><li>‘ potato’ shape nucleus, scarse pale cytopasm </li></ul><ul><li>Processes </li></ul><ul><li>- GFAP (glial fibroacidic protein): intermediate filament </li></ul><ul><li>- Perivascular Feet (Foot Process, Vascular End-Feet) </li></ul><ul><li>surrounding blood vessels </li></ul><ul><li>Specialized Astrocytes </li></ul><ul><li>- Bergmann’s gial cell, Muller cell, pituicyte </li></ul>
    48. 60. Protoplasmic Fibrous Synaptic Astrocyte Astrocyte Glomerulus
    49. 61. Oligodendrocyte <ul><li>Perineuronal Satellite Cell </li></ul><ul><li>Interfascicular Cell </li></ul><ul><li>Cell Body </li></ul><ul><li>round, heterochromatic nucleus </li></ul><ul><li>dark cytopasm </li></ul><ul><li> - rER, free ribosome, Golgi complex, mitochondria </li></ul><ul><li>Myelin forming cell in CNS </li></ul><ul><li>- Myelin Sheath </li></ul><ul><li>Each process constitutes a internodal segment </li></ul>
    50. 62. Oligodendrocyte 1. nucleus of oligodendrocyte 2. process of oligodendrocyte 3. myelin sheath 4. axon
    51. 63. Microglia Cell Body slender, indented, heterochromatic nucleus dark cytopasm - prominent secondary lysosome Processes short, highly branched Macrophage (Mononuclear Phagocytic) System Mesenchymal Origin - Blood Monocyte Increased in Inflammation
    52. 64. Microglia 1. nucleus of microglia 2. process of microglia 3. lysosome 4. capillary 5. pericyte
    53. 65. Ependymal Cell Epithelial Cell lining ventricular surface cilia and microvilli on luminal surface simple cuboidal cell with round nucleus Tanicyte basal process, numerous in 3rd ventricle most ependymal cell has basal process (Chung & Lee, 1988) Choroid Plexus Epithelial Cells ion transporting cell: numerous mitochondria
    54. 67. Schwann Cell Slender Cell with small heterochromatic nuclei Myelin forming cell in PNS - Myelin Sheath: Myelinated Fiber A Schwann cell constitutes a internodal Segment Surround Unmyelinated Axons A schwann cell surround many unmyelinated axons
    55. 68. Schwann Cell
    56. 69. Satellite (Capsular) Cell Squamous Cell encircles neuronal cell body in Ganglion - completely encircles pseudounipolar neuron in spinal and cranial ganglion - neurons of autonomic ganglia were less completely surrounded by satellite cell
    57. 71. <ul><li>Myelin Sheath - MYELIN </li></ul><ul><li>cf. Schwann sheath, Neurilemma </li></ul><ul><li>formed by wrapped plasma membrane of </li></ul><ul><li>Oligodendrocyte in CNS </li></ul><ul><li>Schwann Cell in PNS </li></ul><ul><li>Node of Ranvier - Saltatory Conduction </li></ul><ul><li>evolutionary innovation in chordate </li></ul><ul><li>- conduction velocity </li></ul>Myelin
    58. 72. Myelin Node of Ranvier - Internodal segment Schmidt-Lantermann’s cleft
    59. 75. Osmium tetroxide (OsO 4 ) stain for Myelin
    60. 76. Myelin Structure of fast nerve conduction
    61. 77. Giant squid axon 0.5-1 mm in diameter conduction velocity 25 m/s
    62. 78. Myelin Conduction velocity is proportional to 1. The Length of Internodal Segment 2. Thickness of Myelin 3. Diameter of Nerve Fiber
    63. 79. Conduction velocity of mammalian nerve fiber Group I A  10 - 20 70 -120 Group II A  5 - 12 30 - 70 A γ 3 - 6 15 - 30 Group III A δ 2 - 5 12 - 30 B < 3 3 - 15 Group IV C 0.1 - 1.5 0.5 - 2 Myelinated fiber Unmyelinated fiber
    64. 80. Myelin Formation
    65. 81. Myelin Myelin formation Schwann cell oligodendrocyte
    66. 82. MYELIN - Fusion of Plasma Membrane Major Dense Line - fusion of inner leaflet ---- Myelin Basic Protein (MBP) Intraperiod Line - fusion of outer leaflet ---- Proteolipid Protein (PLP) in oligodendrocyte ---- Protein Zero (P 0 ) in Schwann Cell Myelin
    67. 83. Myelin 1. trilaminar unit membrane 2. major dense line 3. intraperiod line 4. Cytoplasm of Schwann cell
    68. 84. Multiple Slerosis – disease of the myelin Jacqueline Du Pre oligodendrocyte
    69. 85. LEPROSY: Mycobactrium leprae infection of Schwann cell Rembrandt. The King Uzziah Stricken with Leprosy.
    70. 86. Organization of Nervous System Central Nervous System Gray Matter Nucleus and Cortex White Matter Tracts Peripheral Nervous System Nerve (Peripheral Nerve) Ganglion
    71. 87. Peripheral Nerve
    72. 88. <ul><li>Nerve Fiber </li></ul><ul><li>Myelinated Nerve Fiber </li></ul><ul><li> Axon, Myelin sheath , Schwann cell </li></ul><ul><li>Unmyelinated Nerve Fiber </li></ul><ul><li>Axon, Schwann cell </li></ul><ul><li>Connective Tissue Sheath </li></ul><ul><li> Endoneurium </li></ul><ul><li> Perineurium – blood vessels </li></ul><ul><li> Epineurium </li></ul>Composition of Peripheral Nerve
    73. 89. Composition of Peripheral Nerve
    74. 90. Peripheral Nerve Endings: Afferent Endings  R eceptor Neurons of Craniospinal Ganglion Ÿ pseudounipolar neurons of dorsal root ganglia Ÿ trigeminal (semilunar, Gasserian ganglion), geniculate (VII), superior IX, superior X ganglia (GSA) Ÿ geniculate (VII), inferior IX, inferior X ganglia (VA)  Morphological Classification Ÿ free nerve endings Ÿ expanded tip endings Ÿ encapsulated endings ----- CT envestment
    75. 91. Afferent Endings  Free Nerve Endings - Nerve endings without special structural organization - pain and temperature receptor  Expanded Tip Endings - Merkel’s Touch Corpuscle Merkel cells in basal layer of epidermis - Type I Hair cells of Vestibular Labyrinth
    76. 92. Afferent Endings  Encapsulated Endings - Meissner’s Corpuscle - Pacinian Corpuscle (Corpuscle of Vater-Pacini) - Genital Corpuscle - Ruffini’s Ending - End Bulb of Krause - Golgi tendon organ: Proprioceptor
    77. 93. Receptor Endings Ÿ Free nerve ending Ÿ Expanded tip ending Ÿ Encapsulated ending
    78. 94. Merkel’s Touch Corpuscle Ÿ expanded tip ending Ÿ Merkel cell - clear cell located in the basal layer of epidermis - membrane bound electron dense granules resembles synaptic vesicle
    79. 95. Meissner’s Corpuscle
    80. 96. Pacinian Corpuscle
    81. 97. Other Encapsulated Endings End Bulb of Krause Genital Corpuscle Lingual Corpuscle
    82. 98. Efferent Endings Somatic Efferent Endings Neuromuscular Junction (Myoneural Junction, Motor End Plate) Autonomic Efferent Endings Endings on smooth muscle and blood vessels
    83. 99. Neuromuscular Junction (Myoneural Junction, Motor End Plate) NMJ M N
    84. 101. Neuromuscular Junction (Motor End Plate)
    85. 102. Myasthenia Gravis <ul><li>muscle weakness </li></ul><ul><li>which is greatly </li></ul><ul><li>increased by exertion or </li></ul><ul><li>repeated contraction </li></ul><ul><li>autoimmune disease </li></ul><ul><li>with autoantibodies </li></ul><ul><li>against Ach receptor </li></ul><ul><li>maybe fatal if untreated </li></ul><ul><li>by respiratory paralysis </li></ul><ul><li>treated with </li></ul><ul><li>AchT inhibitors , </li></ul><ul><li>thymectomy, and </li></ul><ul><li>corticosteroids </li></ul>Defects in NM Transmission before treatment after treatment
    86. 103. Autonomic Efferent Endings
    87. 104. Neuromuscular Spindle <ul><li>Both receptor and effector </li></ul><ul><li>Structure </li></ul><ul><li>1. Capsule </li></ul><ul><li>2. Intrafusal Muscle Fibers </li></ul><ul><li>- Nuclear Bag Fiber </li></ul><ul><li>- Nuclear Chain Fiber </li></ul><ul><li>3. Receptor and Effector Nerve Endings </li></ul><ul><li>- Afferent Ending </li></ul><ul><li>- Efferent Ending </li></ul>
    88. 105. NB: nuclear bag fiber IF: intrafusal muscle fiber CA: capsule EF: extrafusal muscle fiber
    89. 106. Neuromuscular Spindle <ul><li>INTRAFUSAL MUSCLE FIBERS </li></ul><ul><li>(1) Nuclear Bag Fiber </li></ul><ul><li>- 1-4 / each spindle </li></ul><ul><li>- longer and thicker than nuclear chain fiber </li></ul><ul><li>- large central aggregation of nucleus in </li></ul><ul><li> equatorial region </li></ul><ul><li>(2) Nuclear Chain Fiber </li></ul><ul><li>- many fibers / spindle </li></ul><ul><li>- smaller and thinner than nuclear bag fiber </li></ul><ul><li>- central row of nucleus in equatorial region </li></ul>
    90. 107. Neuromuscular Spindle <ul><li>INNERVATION </li></ul><ul><li>Afferent Fibers: Proprioceptors </li></ul><ul><li>(1) Primary (Annulospiral) Endings </li></ul><ul><li>- Group Ia (12-20  m in diameter) afferents </li></ul><ul><li>- terminate in both NB and NC fibers </li></ul><ul><li>- wound around the central equatorial region </li></ul><ul><li>(2) Secondary (Flower-Spray) Endings </li></ul><ul><li>- group II (6-8  m in diameter) afferent </li></ul><ul><li>- terminates predominantly in nuclear chain fiber </li></ul><ul><li>- terminates around juxtaequatorial region </li></ul>
    91. 108. Neuromuscular Spindle <ul><li>INNERVATION </li></ul><ul><li>Efferent Fibers </li></ul><ul><li>Gamma (  ) Motor Fiber </li></ul><ul><li>- terminates in small motor end plates </li></ul><ul><li> of the non-nucleated (striated) region </li></ul><ul><li> of both intrafusal muscle fibers </li></ul>

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