Sialic acid on the surface of photoreceptors and pigment epithelium in RCS rats.

Incubation of isolated retinas and pigment epithelium (PE) from normal and dystrophic RCS rats with colloidal iron (CI) at pH 1.8 resulted in dense labeling of rod outer segments (ROS) and PE surfaces. Pretreatment with neuraminidase reduced subsequent binding of CI. The authors conclude, therefore, that sialic acid residues are localized on the ROS and PE surfaces. In dystrophic rats, uningested ROS tips, which accumulate in the subretinal space, did not bind CI.