Neurilemma

Neurilemma

The neurilemma, also known as the sheath of Schwann, is the outermost layer of the myelin sheath surrounding the axon of a neuron. It is essential for the proper functioning of the peripheral nervous system (PNS).

Structure

Diagram of a neuron showing the neurilemma.

The neurilemma is formed by Schwann cells, which are a type of glial cell in the PNS. These cells wrap around the axon, creating a protective and insulating layer. The neurilemma is the outermost layer of this wrapping and contains the nucleus and cytoplasm of the Schwann cell.

Function

The primary function of the neurilemma is to protect the axon and aid in the regeneration of damaged nerve fibers. Unlike the central nervous system (CNS), where oligodendrocytes form the myelin sheath, the PNS has the ability to regenerate damaged axons, largely due to the presence of the neurilemma.

Role in Nerve Regeneration

When a nerve fiber is damaged, the neurilemma plays a crucial role in the repair process. It forms a regeneration tube that guides the growth of the new axon, allowing it to reconnect with its target cells. This regenerative capability is a key difference between the PNS and the CNS, where such regeneration is limited.

Clinical Significance

Damage to the neurilemma can result in impaired nerve function and delayed healing of nerve injuries. Conditions such as Guillain-Barré syndrome and Charcot-Marie-Tooth disease can affect the neurilemma, leading to neurological symptoms.

Related pages

• Myelin
• Schwann cell
• Peripheral nervous system
• Axon
• Nerve regeneration