It is customary to credit Rudolf Virchow (1) with the discovery of neuroglia (see ref. 2). As a practicing pathologist who was familiar with inflammatory processes in the brain, Virchow opposed his contemporaries’ assertion that the brain was void of connective tissue. He hypothesized that underneath the single-cell layer of the ependyma, the ventricles were lined with connective tissue cells that were capable of mounting inflammatory responses, and referred to these cells as “Nervenkitt” or “nerve putty.” Although erroneous, this coined term has persisted as the preferred generic term, or in its shortened form “glia,” for a class of nonexcitable brain cells. Classification and histological characterization of the true nature of the various neuroglial types followed the development of impregnation techniques by Golgi and Ramon y Cajal in the late 1800s. By the 1920s, the major forms of glial cells had been recognized and identified. Their basic structures and relationships with other critical parts of the nervous system were also beginning to emerge.