myeliinitön

Myeliinitön is a term encountered in some sources as a reference to the myelin sheath, the insulating layer that surrounds axons in the nervous system. The more common and widely used term is myelin sheath or myelin. In many languages the translation aligns with myelin, and variations may occur in transliteration or regional terminology.

Myelin is produced by glial cells: oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system. It consists of repeating layers of lipid-rich cell membranes wrapped around the axon, forming a compact sheath with relatively low cytoplasmic content between layers.

Function: Myelin increases the speed of electrical impulse conduction along axons by providing electrical insulation and reducing membrane capacitance. The sheath is interrupted at gaps called nodes of Ranvier, where ion channels enable rapid depolarization and saltatory conduction.

Development and maintenance: Myelination begins during fetal development in many tracts and continues after birth, often into adolescence for the CNS. Peripheral myelination occurs earlier in many cases. Damage to myelin, or failure to form it properly, can impair nerve signaling and lead to neurological symptoms.

Clinical relevance: Demyelinating diseases, such as multiple sclerosis in the CNS or Guillain–Barré syndrome in the PNS, involve loss of myelin and impaired conduction. Other inherited disorders, called leukodystrophies, affect the integrity of the myelin sheath. Treatments aim to modulate immune responses and promote remyelination.