Immunohistochemical studies of ovarian and testicular teratomas with antiserum to glial fibrillary acidic protein.

Twenty cases of ovarian or testicular teratomas were studied with a sensitive peroxidase-antiperoxidase (PAP) method utilizing an antibody to glial fibrillary acidic protein (GFAP). Positive staining was restricted to the perikaryon, to extensively distributed neuroglial fibrils, or to ependymal lining cells in 13 of 20 teratomas studied. Positively stained cells were also occasionally observed in the choroid plexus, thus indicating the possibility that such cells also retain the capability of producing GFAP. GFAP-positive material was also found in the tumour cells of an undifferentiated ovarian teratocarcinoma; this tumour was believed to represent an ovarian glioma. It is concluded that the PAP method represents a sensitive and valuable histochemical tool which should be further explored to characterize a functional basis of normal and neoplastic cells. Findings are of particular interest in the "germ cell tumours" in which multiple differentiation patterns may be expressed.