Ectopic Retina in the Optic Nerve of Crj: CD (SD) IGS Rats

Abstract

Ectopic retina was observed histopathologically within the beginning of the optic nerve in 19 of 80 male (23.8%) and 21 of 80 female (26.3%) Crj: CD (SD) IGS rats. No abnormal findings were detected ophthalmoscopically in the optic disk of these affected eyes. The ectopic retinal tissues consisted of irregularly-aggregated photoreceptor cells or of tissue segments of the photoreceptor segment, outer nuclear, outer plexiform, and inner nuclear layers. There were no age-related changes or no sex difference in the occurrence of the lesions. These results suggest that the ectopic retina in the optic nerve in Crj: CD (SD) IGS rats may develop in a congenital manner such as overgrowth of the inner layer of the optic cup.