Oligodendroglia are highly specialised to myelinate axons and ensure rapid electrical conduction of action potentials in the central nervous system (CNS). The oligodendroglial cell lineage comprises mature myelinating oligodendrocytes, together with oligodendrocyte precursor cells (OPCs) and immature premyelinating oligodendrocytes, their numerical density depending on developmental age. In early embryonic and postnatal development, OPCs and immature oligodendrocytes predominate, whereas in the adult CNS, mature myelinating oligodendrocytes comprise over 90% of the lineage, with OPCs making up a small but significant population (3–9%). Adult OPCs provide for myelin repair and plasticity throughout life. Oligodendroglial cells express diverse ion channels and neurotransmitter receptors, together with transporters and gap junctions, which enables these cells to sense and respond to their environment and fulfil their myelinating function as well as providing metabolic and homeostatic support for axons.