مادة بيضاء
OPCs are found in both white and gray matter. However, the number of OPCs is higher in white matter than in gray matter because of a higher rate of proliferation in the former. White matter OPCs proliferate and contribute to adult oligodendrogenesis, while gray matter OPCs are slowly proliferative or quiescent and mostly remain in an immature state. White and gray matter OPCs have different resting membrane potentials and ion channel expression. Gray matter lacks voltage-gated sodium channels while white matter does not and produces action potentials. Cells that produce action potentials can receive signals from other neurons. These differences in OPC function depend on their locations.