Glial Cell Response to Injury

• The order of susceptibility of CNS cells to injury runs, from most to least susceptible:
  1. Neurons
  2. Oligodendroglia
  3. Astrocytes
  4. Microglia
  5. Endothelial cells

Astrocytes

• The response of astrocytes to insult include:
  • Necrosis
  • Astrocytosis
    • An increase in the number of astrocytes (i.e. astrocyte hyperplasia).
  • Astrogliosis
    • An increase in the size of astrocytes (i.e. astrocyte hypertrophy).
  • Gliosis
    • Formation of glial fibres.
    • This is a form of scarring in the CNS.

Oligodendrocytes

• Oligodendrocytes are prone to hypoxia and degeneration
• Oligodendrocytes proliferate around damaged neurons.
  • This is known as satellitosis.
• Death of oligodendrocytes causes demyelination.

Microglial Cells

• Microglial cells can respond in two ways to CNS injury.
  1. They may phagocytose cell debris to transform to gitter cells.
     • Gitter cells are large macrophages with foamy cytoplasm. View images courtesy of Cornell Veterinary Medicine
  2. They may form glial nodules.
     • These are small nodules that occur notably in viral diseases.