Localization of S-100 protein in Müller cells of the retina--2. Electron microscopical immunocytochemistry

The cellular and subcellular distribution of S-100 protein was investigated at the ultrastructural level in the rat retina by the immunocytochemical PAP method. S-100 appeared to be localized in the cytoplasm and nucleus of Müller cells, offering conclusive evidence that in the mammalian retina, the protein is confined to glial cells. S-100, as a marker for Müller cells, may be a useful tool in order to study the cytoarchitecture of the retina in normal as well as in pathologic conditions. In addition, the retina may represent a suitable model for further investigation on the biologic role of S-100.