ABSTRACT
The reaction product of cerium used for. localization of 5'-nuclcotidase (5'- Nase) and p-nitrophenylphosphatase(p-NPPase) is highly electron-dense but lacks sufficient contrast at the light microscopic level. We describe two methods for converting the reaction product of cerium to colored compounds visible by light microscopy. Using the Ce-Pb method and Ce-Pb-AgS method, the reaction prod- ucts of 5'-Nase and p-NPPase in isolated neurons of frontal cortex of rabbit were visualized by light microscopy. Aftcr application of the Ce-Pb-AgS method, surface of isolated neurons exhibtied crystalline precipitates by scanning electron microscopy(SEM). X-ray microanalysis of these crystals revealed the presence of high amounts of Ce, S/Pb and Ag. These results demonstrate that enzyme activity could be verified by SEM in conjunction with elementary microprobe analysis.