Retinal Pigment Epithelium Topography in the Mature Quokka, Setonix brachyurus

Abstract

In this paper we describe cell topography of the retinal pigment epithelium (RPE) for the mature marsupial wallaby, the quokka, Setonix brachyurus. RPE topography was analysed in bleached and stained whole mounted retinae, sampling from the entire surface area. The mature adult quokka RPE has a distinct topography in terms of both cell density and the distribution of multinucleate cells. Peripheral RPE demonstrates the lowest cell density and the greatest proportion of multinucleate cells. In an annulus surrounding central retina, corresponding to equatorial retina, RPE cell density is relatively high and multinucleate cells are at the lowest frequency. Cell density is highest in central temporal retina, in the regions adjacent to some of the highest densities in the neural retina. Other regions of central retina exhibit moderate cell densities. A small proportion of central cells are multinucleate. The RPE topography may result from, or account for, regional differences in susceptibility of this tissue to environmental influences and stressors. Understanding of this topography may throw light on the marked localization of certain human retinal diseases inherent to this tissue.