Journal of Neuroscience, Vol 4, 2425-2433, Copyright © 1984 by Society for Neuroscience
The postnatal reduction of the uncrossed projection from the nasal retina in the cat
DS Jacobs, VH Perry and MJ Hawken
We have investigated the postnatal reduction of the uncrossed projection
from the nasal retina in the cat by injecting horseradish peroxidase into
one optic tract of kittens and cats and retrogradely labeling the cells in
the ipsilateral retina that have an uncrossed projection to the brain. The
newborn kitten has over 600 uncrossed cells in the nasal retina. The number
is reduced to about one-quarter of that value by postnatal day 10. The two
adult cats examined had 75 and 100 of these ipsilaterally projecting nasal
cells. They are distributed all across the nasal retina, and most have the
morphology characteristic of gamma cells. A lesion in one optic tract in
the newborn kitten results in an increase in the number of cells from the
nasal retina with an ipsilateral projection at maturity. There are more of
these cells in the region that has been depleted of ganglion cells by the
lesion. This excess consists mostly of gamma and epsilon cells. These
findings indicate that competitive factors play a role in the elimination
of inappropriate ganglion cell projections in the cat, and that this
process contributes to the precision of the nasotemporal division of the
retina.