Plasma membrane expansion: a neuron's Herculean task

The formation of axons and dendrites and maintenance of the neuron's vastly expanded surface require the continuous addition of new membrane. This is achieved by membrane synthesis through the secretory pathway followed by regulated vesicle fusion with the plasma membrane, typically in the distal neurite. However, it is far from simple: multiple distinct membrane carriers are used to target specific membrane domains, dendrites seem to operate semi-autonomously from the rest of the neuron, and exocytosis for membrane expansion is different from that for release of synaptic vesicles. Current knowledge of this process and its implications for neuronal development, function and repair are reviewed.