Neuronal intermediate filament α-internexin is expressed by neuronal lineages in the developing chicken retina

α-Internexin, a neuronal intermediate filament (IF) protein that is expressed in most neurons at the beginning of differentiation, has been studied in the developing vertebrate retina. It has been suggested that α-internexin plays a role in neuroplasticity during development. However, the expression of α-internexin in the chicken retina has not been investigated. In this study, we identified the expression patterns of the chicken α-internexin (chkINA) and neurofilament (NF) proteins in the developing chicken retina. These proteins exhibited dynamic patterns of expression with the progression of retinal development. Expression of chkINA was detected in the processes of ganglion, amacrine, and horizontal cells throughout development. chkINA was also transiently expressed in photoreceptor and bipolar cell lineages. NF triplet proteins exhibited more restricted expression patterns than did chkINA during development. Our observations suggest the coexpression of chkINA and NF triplet proteins in ganglion and amacrine cells in the developing retina, as well as in horizontal cell processes in the adult chicken retina. Our results indicate that chkINA is transiently expressed in all neuronal lineages in the developing chicken retina. These findings provide novel information on chicken retinal cell development and suggest that chkINA is a good neuronal marker for the study of retinal differentiation.