An example of a myelin producing cell in the CNS is oligodendrocyte
The major function of oligodendrocytes is the formation of myelin
Myelin acts as an insulator of axonal segments and is a prerequisite for the high velocity of nerve conduction
Larger axons form thicker myelin
During development, oligodendrocytes arise from precursors located in the sub-ventricular zone such as the sub-ventricular zone of the lateral ventricles for the cerebrum or the fourth ventricle for the cerebellum
In the spinal cord, oligodendrocytes originate from the ventral regions of the neural tube and in the optic nerve they migrate into the nerve from the third ventricle
It is the oligodendrocyte precursor cells which migrate to their destination where they then differentiate into the more mature oligodendrocytes
The proliferation of the oligodendrocyte progenitor cells is controlled by a number of growth factors released predominantly from neurons but also from astrocytes such as platelet derived growth factor (PDGF) or fibroblast growth factor (FGF)
