100] Renewal of photoreceptor cells

Abstract

Publisher Summary This chapter discusses the renewal of photoreceptor cells. Renewal of light-sensitive membranes and their intrinsic visual pigments is a universal feature of visual photoreceptors. This process has been described in vertebrate photoreceptors, but the fundamental events are probably similar in vertebrates and invertebrates. In the case of vertebrate rods and cones, disks are intermittently shed from the outer segment apex and phagocytosed by the adjacent retinal pigment epithelium. In the invertebrate photoreceptors, portions of the microvilli are endocytosed by the photoreceptor itself and degraded by autophagic processes. The visual pigment apoprotein (opsin) is synthesized on the rough endoplasmic reticulum of the visual cell soma and undergoes successive glycosylations in the rough endoplasmic reticulum and Golgi apparatus. In the case of vertebrate rods and cones, disks are intermittently shed from the outer segment apex and phagocytosed by the adjacent retinal pigment epithelium. In the invertebrate photoreceptors, portions of the microvilli are endocytosed by the photoreceptor itself and degraded by autophagic processes.