Confocal micrograph of oligodendrocyte generation. This cross section of an embryonic spinal cord shows the localized area that gives rise to oligodendrocyte precursor cells (yellow). They then migrate out to populate other parts of the spinal cord. Oligodendrocytes 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. Supplied by Nina Callard, courtesy of Wellcome Images.