A new form of hereditary retinal degeneration in Wag/Rij rats.

A spontaneous, hereditable, bilateral retinal degeneration affecting all adult animals in a closed, imbred colony of Wag/Rij rats has been discovered. The disorder is characterized by early onset and a slow progressive course. Early lesions are detected by one month in retinas which are otherwise fully developed. Destruction of the photoreceptor layer proceeds as more and more cells degenerate. Degeneration appears to begin in the photoreceptor cell body and only secondarily affects the outer segment. Futhermore, phagocytic activity of pigment epithelium remains intact until late in the disease. Endstage lesions include retinal disorganization, proliferation and vascularization of pigment epithelium, and migration of pigment epithilial cells into the retina. The temporal and structural characteristics of this retinopathy indicate it may serve as a useful model for study of retinitis pigmentosa in man.