As you’ve been reading about the myelin sheath, you might have been curious about how long those layers of myelin last. A research team was curious about this too and looked at how myelin changes over time. Read the abstract and introduction of their paper Dynamics of Oligodendrocyte Generation and Myelination in the Human Brain in the journal Cell.
As you read, try to find out, how old does myelin get? How old are the oligodendrocytes producing that myelin?