Characterization of the Photoreceptor Population of the Retina of the Bushbaby

摘要

This project was undertaken to determine the characteristics of the photoreceptor population in the retina of the bushbaby (Galago crassicaudatus), as a contribution to assessment of this nocturnal primate retina as a potential model for human scotopic, or night, vision. In particular, detection of cone (photopic) photoreceptors and, if detected, estimates of their frequency were primary objectives. Retinas of eight Galago were examined by light and/or electron microscopy. Presence of cones was considered established if photoreceptors meeting four traditional structural criteria could be found and if one or more of the 'cone-specific' procedures could be shown to selectively label photoreceptors. Structures meeting two of the four anatomical criteria were identified. These were pedicle-type synaptic endings and cone-like nuclei. These are not sufficient conditions to prove presence of cones. None of the cone-specific procedures selectively labelled any photoreceptors in the Galago retinas, although all clearly selectively labelled cones in the retinas of the control species. The evidence from this study does not support the presence of cones in the Galago retina. These results indicate that the Galago retina offers significant potential as a model scotopic system.