The neurilemma plays which role in the peripheral nervous system?

The neurilemma plays which role in the peripheral nervous system?

• A. forms the blood-brain barrier
• B. wraps CNS axons
• C. helps PNS axons regenerate
• D. speeds conduction along axons

Answer: (C)

The neurilemma is the outermost layer surrounding a peripheral nerve fiber, formed by the cytoplasm of Schwann cells. This structure is essential for regeneration in the peripheral nervous system because it creates a regeneration tube that guides the regrowth of axons after injury and provides supportive signals to promote healing. In contrast, the blood-brain barrier is a CNS feature built from endothelial tight junctions with astrocyte endfeet, not neurilemma. CNS axons are wrapped by oligodendrocytes, not by Schwann cells, so there isn’t a neurilemma around them. And while myelin speeds conduction, that effect comes from the myelin sheath itself, not from the neurilemma. Thus, the neurilemma’s role is to help PNS axons regenerate.

The neurilemma is the outermost layer surrounding a peripheral nerve fiber, formed by the cytoplasm of Schwann cells. This structure is essential for regeneration in the peripheral nervous system because it creates a regeneration tube that guides the regrowth of axons after injury and provides supportive signals to promote healing. In contrast, the blood-brain barrier is a CNS feature built from endothelial tight junctions with astrocyte endfeet, not neurilemma. CNS axons are wrapped by oligodendrocytes, not by Schwann cells, so there isn’t a neurilemma around them. And while myelin speeds conduction, that effect comes from the myelin sheath itself, not from the neurilemma. Thus, the neurilemma’s role is to help PNS axons regenerate.