Journal of Neuroscience, Vol 8, 3151-3159, Copyright © 1988 by Society for Neuroscience
Micropruning: the mechanism of turning of Aplysia growth cones at substrate borders in vitro
DW Burmeister and DJ Goldberg
Department of Pharmacology, Columbia University College of Physicians and Surgeons, New York, New York 10032.
Growth cones of Aplysia californica neurons were observed with video-
enhanced contrast-differential interference contrast (VEC-DIC) microscopy
as they turned at a border between poly-L-lysine-treated and untreated
glass. Growth cones that turned generally developed 2 distinct active areas
of filopodial and veil formation, much in the way of growth cones
undergoing branching. Both active areas advanced, but turning of the
neurite occurred through the selective resorption of the incipient branches
developing on the untreated substrate. Thus, micropruning of developing
regions of the growth cone, rather than the asymmetric extension of
filopodia or veils, was primarily responsible for directing neurite growth.
We present the hypothesis that abrupt turns by growing neurites are
mediated by 2 sets of signals, one causing growth cone splitting, and a
second set regulating the survival of the separate branches.
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