Immunocytochemical localization of S-100 protein in interstitial cells of the monkey Macaca irus pineal gland.

Pineal interstitial cells of the monkey Macaca irus were shown to react with an anti-human S-100 protein antibody, using the indirect immunoperoxidase technique on sections of paraplast-embedded pineal glands. Immunoreactivity was seen in the cytoplasm of the cells, stellate in shape and intermingled with pinealocytes; the latter did not stain with the antiserum against S-100 protein. Immunoreactivity was also present in the nuclei, as was reported in various other cell types immunostained with anti-S-100 protein antibodies. The present results support the view that interstitial cells of the monkey Macaca irus pineal gland may be of astroglial origin.