Chapter 7 – White Matter Structure: A Microscopist’s View

The white matter of the central nervous system comprises axons, their myelin sheaths, and glial cells. Of the glial populations, oligodendrocytes, which produce the myelin sheath, and their progenitors, are the most abundant. The other major glial cell types are astrocytes and microglia. Here we provide an overview of these cellular elements, including their functions, microstructural features, and relationships to one another. We also briefly describe some of the changes that occur in response to injury to these white matter elements.