Axonal transport

Abstract

Axons are long slender cylindrical projections of neurons that enable these cells to communicate directly with other cells in the body over long distances, up to a meter or more in large animals. Remarkably, however, most axonal components originate in the nerve cell body, at one end of the axon, and must be shipped out along the axon by mechanisms of intracellular motility. In addition, signals from the axon and its environment must be conveyed back to the nerve cell body to modulate the nature and composition of the outbound traffic. The outward movement from the cell body toward the axon tip is called anterograde transport and the movement in the opposite direction, back toward the cell body, is called retrograde transport. This bidirectional transport, known collectively as axonal transport, is not fundamentally different from the pathways of macromolecular and membrane traffic found in other parts of the neuron, or indeed in any eukaryotic cell, but it is unique for the volume and scale of the traffic required to maintain these long processes.