Ultrastructure of the surface of the epithelial cells in the rat retina

Summary The epithelial cells in the retina of rats were examined by scanning and transmission electron microscopy.The apical surface of the epithelial cells is covered by a large number of microvilli, which are embedded in an extracellular material. Distinct holes remaining after detached photoreceptor cell segments are numerous. The cells are polyhedronal, usually hexagonal and holes are scattered in their plasma membrane. Many of the epithelial cells are binucleated. The borders between adjacent cells are always close to each other. Numerous cytoplasmic folds or foot processes occur at the base of the cells as well as an extracellular space.The characteristic surface structures are discussed in relation to the function of the retinal epithelial cells.Supported by grants from the Swedish Medical Research Council (B70-12X-2543-02) and Riksföreningen mot Cancer (69171, 265-B69-01X).