The neuroglia cells that produce myelin are the oligodendrocytes. Myelin, which is needed for the high - velocity transmission of impulses along nerve cells, has been found to be less ubiquitous then previously thought according to recent research by Harvard scientists.
All vertebrates have oligodendrocytes except for the jawless fish like lampreys and hagfish, and the major function of these cells is to produce myelin. The formation of myelin starts in humans within the latter half of fetal life and begins in the spinal cord area. It continues up to the age of 20. Peak activity for human myelin formation is during the first year post natally.