FIGURE 5.4 Faster and Faster Myelination is a lifelong process. Shown here is a cross-section of an axon (dark middle) coated with many layers of Schwann cells, as more and more myelin wraps around the axon throughout childhood. Age-related slowdowns in adulthood are caused by gradual disappearance of myelin layers.

DR. DAVID FURNESS, KEELE UNIVERSITY/SCIENCE SOURCE