Oligodendrocyte Marker O4: ProductsOligodendrocytes are myelinating cells within the central nervous system (CNS) that form the myelin sheath of axons to support rapid nerve conduction. Oligodendrocyte Marker O4 is an antigen on the surface of oligodendrocyte progenitors. O4 has been commonly used as the earliest recognized marker specific for the oligodendroglial lineage. The monoclonal antibodies A2B5, O4, and O1 are frequently used to define distinct stages in the maturation of oligodendrocyte progenitors. In general, A2B5+/O4- defines the most immature oligodendrocyte precursors, O4+/O1- defines intermediate precursors, and O1+ defines oligodendrocytes at a more mature stage. In many CNS disorders, such as stroke, multiple sclerosis, and spinal cord injury, demyelination of axons contributes to functional deficit.