A developmental process whereby a protective fatty material wraps around nerve cells.

Myelinization is a gradual developmental process whereby a protective, fatty material called myelin wraps around nerve cells in the peripheral and central nervous system. The myelin sheath protects the nerve fibers in much the same way as insulation covering electrical wiring. Although the process can take up to 10 years to reach completion, the bulk of myelinization occurs during the fetal and infancy stages.

Several degenerative diseases can result when the myelin sheath is destroyed. The most common is multiple sclerosis (MS), which affects 250,000 people in the United States. MS occurs when deviant white blood cells destroy the myelin layers. Sclerotic plaque forms on the fibers, short-circuiting electrical signals in the nervous system. Victims of the disease may suffer recurring episodes of numbness and muscle weakness, uncontrollable tremors, slurred speech, loss of bowel and bladder control, memory...