Enriched Environment Effects on Myelination of the Central Nervous System: Role of Glial Cells

Figure 2

Myelination and remyelination of glial cells in the CNS. In the process of myelination, NPC matures into OPC, OPC proliferates and differentiates into immature OL, which then forms myelin sheaths that wrap axons, and astrocyte and microglia release various molecules to control the development of OL and myelination. When the myelin sheath is damaged and repaired, OPC proliferates and differentiates to supplement OL, astrocytes and microglia enter an activated state, and both exhibit dual activities, inducing harmful or beneficial effects. In addition, microglia can swallow fragments of the myelin sheath. The green arrows indicate molecules exhibiting positive activity on oligodendrocyte lineage and myelin production, whereas the red arrows indicate molecules displaying inhibiting activity on oligodendrocyte lineage production.