According to About.com "Glial cells are non-neural cells that perform "housekeeper" functions
such as clearing out debris and excess materials. Glial cells support
neurons by providing support and nutrition. There are several different
types of glial cells: astrocytes, oligodendrocytes, microglia,
ependymal cells, radial glial, satellite cells and schwann cells. It is
estimated that there are 10 to 50 times more glial cells than there are
neurons in the brain."