A barium method for the cytochemical detection of sulfated glycosaminoglycans in mast cells and basophilic leukocytes

Barium ions precipitate inorganic as well as organic sulfate compounds and they can be detected by a reaction with sodium rhodizonate. In this work, w e describe the use of a barium method for the selective demonstration of su lfated glycosaminoglycans in cytoplasmic granules of mast cells and basophi lic leukocytes. Methanol-fixed smears of mouse peritoneal mast cells and ra t bone marrow basophils were treated with 5 % BaCl2 for 10 min, followed by staining with either 0.2% sodium rhodizonate in 50% ethanol for 2 h at 60 degrees C or 0.01 % brilliant green in distilled water for 1 min. Light mic roscopic observation revealed a strong staining reaction of the cytoplasmic granules of these cell types, which was more selective when using sodium r hodizonate. Control smears treated with BaCl2 or sodium rhodizonate alone, and those subjected to methylation/extraction of sulfate groups before stai ning remained unstained. The selective binding of barium ions to mast cell granules was established with scanning electron microscopy using a backscat tered electron detector, and confirmed by energy dispersive X-ray microanal ysis:as well as element mapping.