Electron microscopic study on S-100 protein-immunoreactive cells in the guinea pig duodenum, with special reference to the interstitial cells of Cajal.

S-100 protein-immunoreactive cells were studied in the nervous system of the guinea pig duodenum by pre-embedding immunoelectron microscopic cytochemistry. Immunoreactivity of S-100 protein was found diffusely in the cytoplasm of enteroglial cells in the ganglia, nerve strands and autonomic ground plexus. There were fibroblast-like cells containing no S-100 protein immunoreactivity around the ganglia and nerve bundles. Relationship between the fibroblast-like cells and the interstitial cells of Cajal was discussed.