Axoneja

Axoneja refers to axons, the elongated processes of neurons that transmit electrical impulses away from the cell body. They serve as the primary conduits for information within the nervous system, connecting the cell body to synapses on other neurons, muscles, or glands.

Anatomy and conduction: Axoneja typically originate at the axon hillock and extend through the cytoplasm, supported by cytoskeletal elements. In many vertebrates, they are insulated by myelin, produced by oligodendrocytes in the central nervous system and by Schwann cells in the peripheral nervous system. This myelination enables saltatory conduction, increasing the speed of action potential transmission. At regular intervals, nodes of Ranvier facilitate rapid signal propagation along the fiber.

Transport and signaling: Inside axoneja, molecular motors move cargo along microtubules in two directions: anterograde transport from the soma to the terminals and retrograde transport back to the cell body. This transport supports synaptic function, maintenance, and signaling during development and after injury. Axonal transport also contributes to the propagation of signals that influence neuron survival and plasticity.

Development and disease: During development, growth cones explore the environment to guide axoneja toward target regions, guided by cues such as netrins, semaphorins, and neurotrophins. Axonal damage or degeneration occurs in many conditions, including trauma, stroke, and neurodegenerative diseases, and can disrupt neural connectivity and function. Understanding axoneja structure and function is central to neuroscience and clinical neurology.

See also: neuron, synapse, myelin, axonal transport.