Journal of Neuroscience, Vol 4, 2823-2829, Copyright © 1984 by Society for Neuroscience
The spatial control of ganglionic neurite growth by the substrate- associated material from conditioned medium: an experimental model of haptotaxis
F Collins and MR Lee
Techniques are described for forming on the culture substrate a narrow
pathway of material derived from medium conditioned by embryonic non-
neuronal cells. There is a precise correlation between the known location
of the pathway and the spatial distribution of neurites extended from whole
ciliary ganglia or dissociated neurons grown on the patterned substrate.
When individual growth cones moving on the pathway contact one of its
edges, they turn sharply so as to remain on the pathway. This turning
response is not simply due to a physical barrier to movement across the
edge, since growth cones can cross onto the pathway when entering from the
adjacent untreated substrate. The strong preference for neurites to
maintain contact with the pathway also is not simply a result of their
inability to survive or elongate outside of the pathway, since neurites
from whole ganglia elongate readily on other regions of the substrate,
although their growth is then undirected. Direct contact with the pathway
is required for these directive effects, and there is no indication that
the material bound to the substrate diffuses off and exerts its effects at
a distance. The neurite-guiding activity is found in partially purified
fractions of conditioned medium which also contain a substrate-bound
inducer of neurite outgrowth. It is possible that both activities may be
due to the same components of conditioned medium. These results suggest
that ciliary ganglion growth cones are able to detect specific components
of conditioned medium on the substrate and respond to their presence by
changing their direction of movement so as to remain in contact with these
components.(ABSTRACT TRUNCATED AT 250 WORDS)