Myelinisierte

Myelinisierte is the German adjective meaning myelinated. In neuroscience, it describes axons or nerve fibers that are covered with a myelin sheath, a lipid-rich layer that insulates and speeds electrical signaling. In the central nervous system, myelin is formed by oligodendrocytes; in the peripheral nervous system, by Schwann cells. The sheath typically covers many segments of an axon, with gaps known as nodes of Ranvier.

The primary function of myelination is to increase the speed of nerve impulse conduction through saltatory conduction, where impulses jump from node to node. Myelin also helps conserve energy by reducing the membrane area that needs ion exchange during signaling, contributing to metabolic efficiency in transmission.

Myelination develops in a region- and age-dependent sequence. Some pathways begin to myelinate prenatally, while others continue after birth, often into adolescence. Different fiber tracts achieve varying levels of myelination, influencing the maturation of sensory, motor, and cognitive functions. Not all axons are myelinated; small-diameter fibers often remain unmyelinated or only partially myelinated.

Clinical relevance arises when myelin is damaged or lost. Demyelinating diseases disrupt signal transmission and can lead to sensory and motor deficits. The central nervous system can be affected by conditions such as multiple sclerosis, whereas the peripheral nervous system is impacted by diseases like Guillain–Barré syndrome. Remyelination can occur, but the process may be incomplete, which can contribute to lasting neurological impairment if axons degenerate.