STRUCTURE AND COMPOSITION

• Myelin Sheath is made up of Myelin which is an insulating material made up of lipids.
• Process of Myelination starts inside womb of mother slowly but most of it  occurs rapidly in infancy and continues throughout Adolescence.
• Myelin is formed by the help of Schwann Cells mostly. However in Central Nervous System Myelination occurs by the Oligodendrocytes around the Axons.
• Myelinated fibres are white in colour thats why form White Matter of the Nervous System.
• Myelin Sheath appears like sausages around the length of Axon and small gaps between them. Each of this structure wraps the Axon in a continuous circular fashion.

FUNCTION AND SIGNIFICANCE

• Myelin Sheath serves to insulate the axon along its way. There are small gaps between adjacent Myelin Sheaths through which conduction hence signal transmission can occur. Nerve Signals travel through these gaps in a jumping fashion and this type of transmission is fast. Hence it is an important component of nervous system.
• If a peripheral neuron is damaged, Myelin Sheath can provide a path for regrowth of Axon. However it is not perfect.
• Damage to Myelin Sheath often results in loss of the neuronal function.
• Myelin Sheath can degenerate in certain diseases of CNS. For Example Autoimmune Diseases like Multiple Sclerosis, Neuromyelitis Optica, Guillain-Barre’ Syndrome etc.