Genetic control of retinal ganglion cell projections

Authors

  • Jennifer H. Lavail,

    1. Department of Neuroscience, The Children's Hospital Medical Center, Boston, Massachusetts 02115
    Current affiliation:
    1. Department of Anatomy, The University of California, San Francisco, California 94143
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    • Part of this work was carried out while the authors were at their current addresses

  • Ralph A. Nixon,

    1. Department of Neuroscience, The Children's Hospital Medical Center, Boston, Massachusetts 02115
    Current affiliation:
    1. Ralph Lowell Laboratories, McLean Hospital, Belmont, Massachusetts 02178
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    • Part of this work was carried out while the authors were at their current addresses

  • Richard L. Sidman

    1. Department of Neuroscience, The Children's Hospital Medical Center, Boston, Massachusetts 02115
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Abstract

We have assessed the effects of 15 pigmentation mutations on the development of retinal ganglion cell projections in mice in two ways: (1) by analyzing the pattern of innervation of the ipsilateral lateral geniculate nucleus as mapped in autoradiograms of brains of animals killed 12 days after intravitreal injection of 3H-proline into one eye and (2) by determining the ratio of axonally transported radioactive protein in the contralateral and ipsilateral optic tracts after similar intravitreal injections. Analysis of the ratio of transported protein in the two optic tracts provides a new and useful assay of the degree of decussation in experimental animals. The effects of the mutations on eye pigmentation, whole eye melanin content and relative tyrosinase activity also were examined. The degree of ipsilateral innervation generally correlates with the degree of pigmentation of the retinal pigment epithelium and with tyrosinase activity. However, discrepancies have been found in ch and ce mutants. In these animals the pigment epithelium is well pigmented, and the area of ipsilateral innervation in the lateral geniculate nucleus is extensive, despite a high ratio of label in contralateral to ipsilateral optic tracts and low tyrosinase activity. Furthermore, mice heterozygous for the c2J allele have pigmentation and optic projections that are normal even though tyrosinase is reduced to 40% of normal. The few anomalous results suggest that alternative or additional factors may control optic axon projections.

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