Light microscopical localization of enzymes by means of cerium-based methods. III. Visualization techniques for cerium phosphate.

Cerium-based methods are more and more used for the electron microscopic localization of phosphohydrolases. By means of the earlier described Ce-Pb-technique, it is possible to localize these enzymes on the light microscopical level. The final product of this reaction is lead sulfide. In addition to this technique, other visualization methods for the light microscopically not visible cerium phosphate are proposed. 3 successful techniques are described in the report: The cerium perhydroxide reaction. By means of H2O2 cerium phosphate is converted into cerium perhydroxide which has an orange-yellowish colour. The manganese dioxide reaction with the conversion of cerium phosphate into cerium oxalate, which is able to reduce permanganate into the hardly soluble brown coloured manganese dioxide. A silver technique (Ce-Pb-AgS-method), which is characterized by the conversion of cerium phosphate into lead phosphate and in a second step to lead sulfide. At the active sites of the lead sulfide, the reduction of silver ions takes place. The reduced silver is converted in a final step into silver sulfide. The enzyme activity is represented by a brown or black coloured staining.