Forward plasma membrane flow in growing nerve processes.

Nerve growth requires addition of new plasma membrane material, which is generally believed to occur at the growth cone. Local incorporation of a fluorescent lipid analog into the plasma membrane of fast-growing Xenopus neurites revealed an anterograde bulk membrane flow that correlated with neurite elongation. The rate of membrane flow depended on the position of the labeled membrane segment along the neurite, increasing with distance from the soma. This result suggests that new membrane in growing Xenopus neurites is added not at the growth cone but at the cell body and along the neurite.