EVERYDAY SCIENCE

Detailed explanation-1: -In most neurons, the axon is surrounded by a white insulating sheath called myelin or medullary. The outermost thin sheath covering of the axon is called neurilemma.

Detailed explanation-2: -The myelin sheath itself is the inner portion of these wrappings (approximately 100 layers of plasma membrane), and the outermost layer that contains the nucleus and cytoplasm is the neurilemma (also called the neurolemma, sheath of Schwann, and Schwann’s sheath).

Detailed explanation-3: -In the peripheral nerves, the neurolemma is the outer covering of nerve fibers. The myelin sheath of the axon is surrounded by a nucleated cytoplasm layer of Schwann cells. The neurilemma is only seen in the peripheral nerves because Schwann cells are only present in the peripheral nerves.

Detailed explanation-4: -Schwann cells, also called neurolemmocytes, have two structural types. They may form a thick myelin sheath, or an indented plasma membrane that folds around peripheral axons in the PNS. Where a Schwann cell covers an axon, the outer cell surface is called the neurilemma. This shields the axon from interstitial fluids.