Journal of Neuroscience, Vol 4, 1414-1428, Copyright © 1984 by Society for Neuroscience
Paths of axons in the visual system of perciform fish and implications of these paths for rules governing axonal growth
AC Rusoff
The optic nerve of many perciform fish is ribbon-shaped, and axons from
ganglion cells in specific parts of the retina are consistently found in
specific places in this ribbon. I utilized this organization to fill
selected groups of axons with horseradish peroxidase. I then traced these
groups of axons through the nerve and across the tectum to their terminal
arbors. The paths of the axons suggest that axons use a number of different
mechanisms to guide them to their correct terminal sites. At some points
they appear simply to grow along the surface created by earlier axons, but
at other points they seem to be using cues more complex than simple
mechanical guidance. In addition, I have demonstrated that for every anulus
of ganglion cells on the retina there is an anulus of terminal arbors on
the tectum. With time the terminals in a given anulus must move caudally to
keep the retinotopic map centered on the tectum while the tectum continues
growing nonsymmetrically . I have shown both that the anuli of terminals do
remain roughly centered on the tectum and that the predicted pattern of
terminal movement is visible on the tecta of perciform fish.