Double labeling immunohistochemical technique provides evidence of the specificity of glial cell markers.

Sequential treatment of rat cerebellar slices with two antisera, each specific for a different glial cell marker, revealed, by indirect immunofluroescence combined with the immunoperoxidase method on the same tissue section, that carbonic anhydrase isoenzyme II (CA II) is exclusively localized in oligodendrocytes while the glial fibrillary acidic protein (GFA) is, as well established, a specific marker for astrocytes.