Journal of Neuroscience, Vol 2, 339-353, Copyright © 1982 by Society for Neuroscience
The transplantation of eyes to genetically eyeless salamanders: visual projections and somatosensory interactions
WA Harris
Eyes were transplanted from normal axolotls to eyeless mutants, and several
anatomical and physiological observations were made on the central visual
centers in these animals. Some central projections were bilateral to the
optic centers of the thalamus and midbrain, some traveled ipsilaterally to
the same centers, and the rest grew down the spinal cord. This is similar
to what has been found in eyes transplanted to normal hosts. The type of
projection made in eyeless hosts correlated with the site of nerve entry
into the CNS as in control hosts. Thus, the transplanted projection did not
appear to be influenced by the host's optic nerves and tracts or lack of
them. In spite of the transplanted optic fibers' taking abnormal paths,
they made normally organized topographic maps on the host tecta. The visual
and somatosensory topographic projections to the tectum were found to be in
near perfect register normally, but in eyeless mutants to which rotated
eyes had been transplanted, they were not. Acetylcholinesterase activity,
found in the primary optic neuropil in normal animals, was greatly
diminished in eyeless mutants, yet normal mutants with grafted eyes.
Finally, transplantation of an eye to an eyeless mutant corrected the
abnormally dark pigmentation caused by eyelessness but only in those cases
of bilateral central innervation.