axonal

Axonal is an adjective used in neuroscience to describe features related to the axon, the elongated process of a neuron that transmits electrical impulses away from the soma to other neurons, muscles, or glands. The axon originates in the axon hillock, may extend long distances, and ends at axon terminals where neurotransmitters are released to synapse with target cells. In the central nervous system, axons are often myelinated by oligodendrocytes; in the peripheral nervous system, by Schwann cells. Myelination increases conduction velocity via saltatory conduction at nodes of Ranvier.

Axons conduct action potentials by propagating depolarization along their membrane. Propagation speed depends on axon diameter and degree of myelination. In addition to electrical signaling, axons are active in transport processes: anterograde transport moves materials from the soma toward the terminals, retrograde transport returns substances to the cell body. Microtubules, supported by motor proteins such as kinesin and dynein, power this bidirectional movement, powered by ATP.

Axonal injury or degeneration can disrupt neural circuits. Wallerian degeneration follows axonal transection distal to the injury site. Because of limited intrinsic regenerative capacity in the central nervous system, axonal regeneration is restricted there, whereas peripheral axons show greater regrowth under favorable conditions. Axonal pathologies contribute to various neurodegenerative and neuropathic conditions, including amyotrophic lateral sclerosis, traumatic brain injury, and peripheral neuropathies.