GLIAL LINEAGES AND MYELINATION IN THE CENTRAL-NERVOUS-SYSTEM

Oligodendrocytes, derived from stem cell precursors which arise in sub ventricular zones of the developing central nervous system, have as th eir specialist role the synthesis and maintenance of myelin. Astrocyte s contribute to the cellular architecture of the central nervous syste m and act as a source of growth factors and cytokines; microglia are b one-marrow derived macrophages which function as primary immunocompete nt cells in the central nervous system. Myelination depends on the est ablishment of stable relationships between each differentiated oligode ndrocyte and short segments of several neighbouring axons. There is gr owing evidence, especially from studies of glial cell implantation, th at oligodendrocyte precursors persist in the adult nervous system and provide a limited capacity for the restoration of structure and functi on in myelinated pathways damaged by injury or disease.