Human brain the largest cells (by size of cell body) in the nervous system. The adult human brain is estimated to contain 86±8 billion neurons, with a roughly equal number (85±10 billion) of non-neuronal cells. Out of these neurons, 16 billion (19%) are located in the cerebral cortex, and 69 billion (80%) are in the cerebellum. Types of glial cell are astrocytes (including Bergmann glia), oligodendrocytes, ependymal cells (including tanycytes), radial glial cells and microglia. Astrocytes are the largest of the glial cells. They are stellate cells with many processes radiating from their cell bodies. Some of these processes end as perivascular
Radial glial cell visualized using the electron microscope or high-resolution time-lapse microscopy, through which neurons can be seen tightly wrapped around radial glia as they travel upwards through the cortex. Additional evidence suggests that many neurons may move between neighboring radial glial fibers during migration. While excitatory neuronal migration is largely radial, inhibitory, GABAergic neurons have been shown to undergo tangential migration. Tangentially migrating neurons also appear to initiate contact with radial glial fibers in the developing cortex of ferrets, implicating radial glial cells in both of these forms of migration. As radial glia seem to differentiate late in spinal cord development, near