The human visual cortex, especially its ganglionic lamina, was found to contain many neurons with perineuronal sulfated proteoglycans which were stained with cationic iron colloid and aldehyde fuchsin. It also contained many neurons with surface glycoproteins labeled with lectin Vicia villosa agglutinin (VVA) or Glycine max agglutinin (SBA). Double staining frequently showed that the neurons stained with cationic iron colloid were not labeled with lectin VVA or SBA. Hyaluronidase and chondroitinase ABC/heparitinase/ keratanase digestions eliminated the perineuronal cationic iron colloid reaction, but never interfered with the cell surface lectin labeling. These findings indicate that the cell surface glycoproteins reactive to lectin VVA or SBA are neither structural elements nor adhesive molecules of the proteoglycans. Double staining further demonstrated that in some neurons with perineuronal sulfated proteoglycans, the cytoplasm was labeled with lectin Arachis hypogaea agglutinin (PNA). It was further noticed that the lectin VVA-labeled neurons were not always identical with the neurons labeled with lectin SBA or with lectin PNA.
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