The dithizone,Timm's sulphide silver and the selenium methods demonstrate a chelatable pool of zinc in CNS

Summary From rats intravitally treated with dithizone (diphenyl-thiocarbazone) brains and spinal cords were removed and freeze-dried. The dithizonates present in the CNS tissue were extracted with carbon tetrachloride and subjected to a multielement analysis (proton activation, PIXE). It was found that the extract contained two metals. Most of the metal was zinc, but small traces of copper were also dectected. Because prior treatment with the chelating agent, dithizone, can block both the Timm and the selenium metal staining methods, it is suggested that the three techniques label predominantly zine in the neuropil (DTS-zine).