From Regina Bailey,
Your Guide to Biology.
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Glial cells are cells of the nervous system. They compose a voluminous support system that is essential to the proper operation of nervous tissue and the nervous system.

Unlike neurons, glial cells do not conduct nerve impulses.

Glial Cells

Glia perform a plethora of functions in the nervous system.

These functions include providing support for the brain, assisting in nervous system repair and maintenance, assisting in the development of the nervous system, and providing metabolic functions for neurons.

There are several types of glial cells present in the nervous system of humans:

• Astrocytes
  
  Astrocytes are found in the brain's capillaries and form the blood-brain barrier that restricts what substances can enter the brain.
  
  
• Microglia
  
  Microglia are extremely small cells of the central nervous system that remove cellular waste and protect against microorganisms.
  
  
• Oligodendrocytes
  
  Oligodendrocytes are central nervous system structures that wrap some neuronal axons to form an insulating coat known as the myelin sheath.
  
  
• Schwann Cells
  
  Schwann Cells are peripheral nervous system structures that wrap some neuronal axons to form an insulating coat known as the myelin sheath.
  
  

Oligodendrocytes and Schwann cells indirectly assist in the conduction of impulses as myelinated nerves can conduct impulses quicker than unmyelinated ones.

Interestingly enough, the white matter in the brain gets its color from a large number of myelinated nerve cells.

Animal Tissue Types

To learn more about animal tissues, visit:

• Nervous Tissue
  
• Epithelial Tissue
  
• Connective Tissue
  
• Muscle Tissue

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