Oligodendrocytes (from Greek, meaning cells with a few branches), or oligodendroglia (Greek, few tree glue), are a type of neuroglia. Their main functions are to provide support and insulation to axons  in the central nervous system of some vertebrates, equivalent to the function performed by Schwann cells in the peripheral nervous system. Oligodendrocytes do this by creating the myelin sheath, which is 80% lipid and 20% protein. A single oligodendrocyte can extend its processes to 50 axons, wrapping approximately 1 µm of myelin sheath around each axon; Schwann cells, on the other hand, can wrap around only one axon. Each oligodendrocyte forms one segment of myelin for several adjacent axons.