Oligodendrocytes are also located in both gray and white matter. They are the predominant cell type in white matter where they are often located as rows of cells between groups of neuronal processes. These are termed interfascicular oligodendroglia and are involved in the formation and maintenance of the myelin surrounding the neuronal processes nearby. In gray matter, oligodendroglia are usually located near neurons and, therefore, are known as perineuronal satellite cells. Cell bodies of oligodendroglia are often located near capillaries, but they lack the definite perivascular end feet characteristic of astrocytes.
The processes of oligodendrocytes are fewer and more delicate than astrocytes, and the cell body shape is polygonal to spherical. The oligodendrocyte nucleus is smaller than that of the astrocyte, is eccentrically located in the cell body, contains clumps of chromatin and can be stained by alkaline dyes. The cytoplasm of oligodendrocytes tends to be darker than that of astrocytes with silver stains, and does not contain glial fibrils (although they do contain microtubules).