Histology of Nervous Tissue

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Histology of Nervous Tissue

• PROF. DR. FAUZIAH OTHMAN
• DEPT OF HUMAN ANATOMY

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• Feature of nerves tissue
• Type of cell neuron neuroglia
• General feature of neuron
• Type of neuroglia astrocyte, oligodendrocyte,
  ependymal cell, microglia
• Synapses
• Myelin formation function
• General structure of peripheral nerves
• Ganglia dorsal root ganglia
• autonomic ganglia

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• Nervous system divided into
• Central nervous system (CNS)
• Brain and spinal cord
• Peripheral nervous system (PNS)
• Cranial and spinal nerves locate outside the
  CNS.

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Morphology of typical neuron

• Neuron functional cell of the nervous tissue.
• Cell body or perikaryon - contains the nucleus
  regulates the functioning of the neuron.
• Numerous dendrites and a single axon.
• Contains Nissl bodies in the cytoplasm
• Axon hillock- no Nissl bodies
• Axon cellular process (extension) carries
  impulses away from the cell body.
• Dendrites cellular process (extension)
  carries impulses toward the cell body

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• 2 types of cell
• i) Neurons (nerve cells)
• ii) Supporting cells
• Functions of neurons
• specialized to receive stimuli and to conduct
  electrical impulses to other parts of the system.
• Arranged as an integrated communications network,
  with several neurons in a chain-like fashion
  involved in sending impulses from one part of the
  system to another.

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Neuron Classification

• Structural
• Multipolar most common type in CNS.
• Include all motor neurons and interneurons of
  brain and spinal cord.
• Bipolar- not as common purely sensory.
• Retina of eye, inner ear, olfactory epithelium in
  the upper region of nose.
• Unipolar (formerly known as pseudounipolar)
• Sensory neurons found in numerous craniosacral
  ganglia of the spinal cord.

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Comparison of Structural Classes of Neurons
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Comparison of Structural Classes of Neurons
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Comparison of Structural Classes of Neurons
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The supporting cells (neuroglia or glia)

• Astrocytes
• Oligodendrocytes
• Microglial cells
• Ependymal cells
• Schwann cells
• Satellite cells

CNS
PNS
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Astrocytes

• Largest, most numerous, versatile, and highly
  branched glial cells
• They cling to neurons and cover capillaries
• Functionally, they
• Support and brace neurons
• Anchor neurons to their nutrient supplies
• Guide migration of young neurons
• Control the chemical environment

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Astrocytes
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Microglia

• Microglia smallest, ovoid cells with spiny
  processes
• - phagocytic cells that migrate through the CNS
  and remove foreign and degenerated material

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Ependymal Cells

• Ependymal cells squamous- to columnar-shaped
  cells
• They line the central cavities of the brain and
  spinal column

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Oligodendrocytes

• Oligodendrocytes branched cells that wrap CNS
  nerve fibers
• - Produce myelin in CNS

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Schwann Cells and Satellite Cells

• Schwann cells (neurolemmocytes) form myelin
  sheaths around peripheral axons
• Satellite cells surround neuron cell bodies with
  ganglia

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Synapse

• The region where the terminals come close to
  another cell and transmit the impulse

• A junction that mediates information transfer
  from one neuron
• To another neuron
• To an effector cell
• Presynaptic neuron conducts impulses toward the
  synapse
• Postsynaptic neuron transmits impulses away
  from the synapse

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Myelin formation function

• Whitish, fatty (protein-lipid), segmented sheath
  around most long axons
• Its function
• Protection of the axon
• Electrically insulating fibers from one another
• Increasing the speed of nerve impulse
  transmission

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2 types of neuroglia produce myelin

• CNS Oligodendrocyte
• PNS Schwann cells

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