title: Embryonic appearance of rod opsin in the urodele amphibian eye.
abstract: Notophthalmus (Triturus) viridescens, a urodele amphibian (newt) common to the Eastern United States, is a promising subject for developmental and regeneration studies. We have available a monoclonal antibody shown to be specific in many vertebrates for rod opsin, the membrane apoprotein of the visual pigment rhodopsin. This antibody to an N-terminal epitope, by rigorous biochemical and immunological criteria, recognizes only rod photoreceptor cells of the retina in light-and electron-microscopic immunocytochemistry. To determine the ontogeny and localization of rhodopsin in developing rods as an indicator of function in the embryonic urodele retina, we have utilized this antibody in the immunofluorescence technique on sections of developing N. viridescens. It was applied to serial sections of the eye region of Harrison stage 28 (optic vesicle) through stage 43 (most adult retina histology complete) embryos, and subsequently visualized with biotinylated species antibody followed by extravidin fluorescein isothiocyanate. The first positive reaction to rhodopsin could be detected in two to four cells (total) of the stage 37 embryonic eye, in the region of the central retinal primordium where the photoreceptors will be found. Some indications of retinal outer nuclear and inner plexiform layers could be seen at this time. Later embryonic stages demonstrated increasing numbers of positive cells in the future photoreceptor outer nuclear layer and outer and inner segments, spreading even to the peripheral retina. Nevertheless, by stale 43, no positive cells could be found at the dorsal or ventral retinal margins. Thus, biochemical differentiation of a photoreceptor population in the urodele retina occurs at a stage before retinal histogenesis is complete. The total maturation of retinal rods occurs topographically over a long period until the adult distribution is achieved.
authors.affiliation: Department of Animal Biology, University of Pennsylvania School of Veterinary Medicine, 19104, Philadelphia, PA, USA.|Institut National de la Santé et de la Recherche Médicale, Unité 118, and C.N.R.S. Unité Affiliée 630, 29 Rue Wilhelm, F-75016, Paris, France.
authors.forename: David Stephen
authors.initials: DS
authors.lastname: McDevitt
authors.affiliation: Hubrecht Laboratory, Netherlands Institute for Developmental Biology, Uppsalalaan 8, 3584 CT, Utrecht, The Netherlands.
authors.forename: Samir Kumar
authors.initials: SK
authors.lastname: Brahma
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, Unité 118, and C.N.R.S. Unité Affiliée 630, 29 Rue Wilhelm, F-75016, Paris, France.
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Jeanny
keywords: Amphibia; Development; Photoreceptors; Retina; Rhodopsin