Immunocytochemical localization of fibronectin to the retinal pigment epithelium of the rat.

Fibronectin is an anionic asialoglycoprotein that is found on a variety of cell types. This study was undertaken in an attempt to localize fibronectin to the rat retinal pigment epithelium with ultrastructural immunocytochemistry. Using Fab-HRP conjugates specific for fibronectin, reaction product was localized on the surface of the apical processes and within the cell to GERL. After treatment of tissue by the biotin-avidin method employing ferritin-avidin, ferritin particles marked the apical processes in a quasi-regular distribution. Tufts of particles were separated by a linear distance of 65-85 nm. Fibronectin was not localized to rod outer segments.