The fine structural localization of S-100 protein in rodent cerebellum.

This report describes the first fine structural locations of S-100 protein in the hamster cerebellum. Innovations in tissue fixation as well as tracer preparation enable localization of S-100 protein to several critical cellular and subcellular sites. Certain neuronal elements, Purkinje cells, contain S-100 protein in both cytoplasm and nucleus. Specific membrane structures including plasma membranes and the nuclear membranes of Purkinje cells are strikingly positive. Localization of S-100 protein to the pericapillary astrocytic endfeet as well as regions of the synapse are of particular biological interest. The clear nuclear localization of the molecule suggests a role in the genetic expression of the developing mammalian brain.