Abstract
Abstract: :
Purpose:Mice have become valuable tools for studies on development and disease. With the availability of transgenic models for retinal degenerations, information regarding development and structure of mouse retina has become extremely vital. Development of outer retina is especially interesting to study on the mechanisms involved in neuronal differentiation and synaptogenesis between the photoreceptors and the horizontal cells. Photoreceptors are predominantly involved in hereditary retinal degenerations, and some of the clues to their management may lie in the molecular mechanisms of its development. In this study, we describe the developmental expression for the markers of photoreceptors (recoverin), horizontal cells (calbindin) and the cytoskeletal elements pivotal to the axonogenesis (beta-tubulin and actin). Methods:Developmental expression of recoverin, calbindin and beta-tubulin was detected in developing mouse retina [embryonic day (E) 18.5 to postnatal day (PN) 14], where as f-actin was localized by Phalloidin binding. Results:Recoverin immunoreactive cells were already present in E 18.5 retina and their number increased until PN 14. Neurite projections from the immunoreactive cells towards the OPL were noted at PN 0 and these neurites reached the OPL at PN 7. Also at PN 7 the histological evidence for the differentiation of outer plexiform layer (OPL) first became visible. At PN 14, all the cell bodies in the ONL, as well as the OPL and outer segments, were immunoreactive. Calbindin immunoreactivity was also already present in E 18.5 retinas. In more advanced stages of development their cell density as well as distance from each other did not increase however they got proximally displaced as the ONL developed. Calbindin immunoreactive plexus were seen in OPL at PN 7. Both beta-tubulin and actin were already present in the IPL at E 18.5, but their expression in the OPL at PN 7 was concurrent with the growth of photoreceptor neurites to this location as well as development of the horizontal cell plexus at the OPL. Expression of synaptophysin immunoreactivity was also concurrent with the development of the OPL. Conclusion:Our results describe the developmental expression of recoverin, calbindin beta-tubulin and actin, and suggest that histological differentiation of the OPL in mice retina coincides with the development of calbindin immunoreactive plexus, reaching of photoreceptor terminals, and expression of actin and beta-tubulin at that location.
Keywords: 564 retinal development • 383 cytoskeleton • 517 photoreceptors