Myelin is the primary lipid-rich component of which tissue type?

• A. Peripheral nerve
• B. Cardiac muscle
• C. Cartilage
• D. Liver

Answer: (A)

Myelin is the lipid-rich insulating sheath around axons, formed in the peripheral nervous system by Schwann cells. This high lipid content—providing insulation and enabling rapid saltatory conduction—is a defining feature of peripheral nerves with myelinated fibers. Other tissues listed don’t have myelin as a major component: cardiac muscle is focused on contractile fibers; cartilage is rich in extracellular matrix like collagen and proteoglycans; the liver contains hepatocytes and metabolic structures, not myelin. Therefore, the tissue type with the primary lipid-rich myelin is the peripheral nerve.