Journal of Neuroscience, Vol 5, 1370-1379, Copyright © 1985 by Society for Neuroscience
The influence of retinal afferents upon the development of layers in the dorsal lateral geniculate nucleus of mustelids
RW Guillery, AS LaMantia, JA Robson and K Huang
The extent to which the development of a normal laminated lateral
geniculate nucleus depends upon retinal afferents has been studied in
normal and albino ferrets and in mink. Removal of all retinal afferents
before they invade the nucleus (28 days in utero) or before they establish
distinct monocular terminal fields (newborn, approximately 41 days
post-conception) produces a nucleus that is smaller than normal and poorly
separated from the adjacent perigeniculate and medial interlaminar nuclei.
However, the nucleus is wedge-shaped, resembling a normal adult nucleus, in
which a broad medial binocular segment is distinguishable from a narrower
lateral monocular segment. There is a normal mediolateral gradient of cell
sizes and some signs of a laminar differentiation, cells next to the optic
tract being morphologically distinguishable from cells near the optic
radiation, but no cell-free interlaminar zones are formed. The development
of a monocularly innervated nucleus depends on the size of the surviving
retinal input. In normally pigmented ferrets or mink the crossed
retinofugal component is larger than the uncrossed component. In the
monocular animals one sees essentially a monocular set of geniculate layers
on each side, with an appropriate asymmetry. Each nucleus can be regarded
as representing the survival of those layers which would have been
innervated by the good eye, together with some additional geniculate
territory that appears to be added to the surviving layers as
retinogeniculate axons occupy territory normally innervated by the other
eye. The crossed component of an albino ferret is abnormally large and the
monocularly innervated contralateral nucleus is almost like that of a
normal albino. There is a full complement of geniculate layers and
interlaminar zones, which appears to develop without any binocular
interactions. The ipsilateral retinogeniculate component of albinos is
extremely small. In the monocular albino animals it forms discontinuous
terminal patches, leaving sectors of the poorly differentiated nucleus
uninnervated. These results show that in geniculate development there is a
limited interaction between the two sets of retinal afferents. Each set
plays a well defined and distinctive role, and one can replace the other to
a limited extent only.
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