The main function of oligodendrocytes in the nervous system is to provide myelination for neuronal axons. These specialized glial cells are found in the central nervous system (CNS) and wrap around axons, forming a protective and insulating layer of myelin. This myelin sheath enhances the speed of electrical signal transmission along the axons, facilitating efficient communication between neurons. Oligodendrocytes also play roles in maintaining neuronal health and supporting metabolic functions, making them essential for the overall functionality of the nervous system.