Volume 16, Number 16,
Issue of August 15, 1996
pp. 5106-5116
Copyright ©1996 Society for Neuroscience
Retinal Ganglion Cell Axons Recognize Specific Guidance Cues
Present in the Deafferented Adult Rat Superior Colliculus
Received Jan. 24, 1996; revised May 20, 1996; accepted May 28, 1996.
Mathias Bähr and
Andrea Wizenmann
Neurologische Universitätsklinik and Max-Planck-Institut
für Entwicklungsbiologie, D-72076 Tübingen, Germany
During development, retinal ganglion cell axons establish a
topographically ordered projection from the retina to the superior
colliculus (SC). The putative guidance activities for retinal axons
that operate during embryonic development are not detectable in the
normal adult SC. However, these cues reappear upon transection of the
optic nerve of adult rats. In the present study, we used a modified
version of the ``stripe assay,'' in which membranes from either
anterior or posterior SC alternated with laminin stripes. Temporal
embryonic retinal axons consistently avoid membranes from embryonic
posterior SC, but only rarely from adult deafferented SC. However, they
are attracted to membranes from both embryonic and adult deafferented
anterior SC. Nasal retinal axons only show a significant preference for
membranes from posterior SC after deafferentation. When retinal axons
were offered a choice to grow on membranes either from their embryonic
or their deafferented target regions, they showed a preference for the
deafferented SC. On carpets consisting of laminin and membranes from
normal SC (not deafferented) or nontarget regions (inferior
colliculus), temporal and nasal axons grow either in a random fashion
or show preferences for the laminin stripes.
Our modified version of the classic stripe assay shows specific growth
preferences of embryonic retinal axons for membrane lanes from their
appropriate embryonic or deafferented adult target regions. These
findings suggest that the deafferentation of the SC in adult rats
triggers the reexpression of specific guidance activities for retinal
axons. Those ``attractive'' guidance cues appear to be differentially
expressed in the developing and deafferented SC.
Key words:
retina;
retinotectal system;
development;
retinal ganglion cell;
stripe assay;
guiding cues