An immunocytochemical study on the localization of S-100 protein in the retina of rats.

The localization of S-100 protein in the retina was studied by immuno-electron microscopy. The immunoreaction for S-100 is specifically confined to Müller cells and astrocytes. Long slender cytoplasmic processes of Müller cells and their participation in the formation of the inner and outer limiting membrane were clearly demonstrated with this immunoreaction. The cytoplasmic processes were also revealed to form continuous sheets surrounding blood vessels. Some somata of Müller cells were found in the outer nuclear layer. The results show that immunostaining for S-100 is useful for selective visualization of Müller cells in the mature retina.