Methods: For the histochemical localization of cerium perhydroxide, gingival tissue sections of patients were treated with 1.0mM CeCl3, and 10mM NaN3. Following the cytochemical reaction procedures mentioned above, tissue pieces were fixed in 2% GA-2% pFA at 4˚C for 60 min, and embedded in Quetol 653. We used an EF-TEM (LEO LIBRA 120) operated at 100 kv. To analyze ESI, energy-filtered images of each elements were recorded by slow scan CCD camera linked to a computer. The ESI of the Ce element were obtained from the DEmax at 907 eV of M4 edge. To quantitative identify the weak edges, the background was stripped using a two-window method. ESI analysis of phosphorus (P) element (DEmax 153.5 eV of L2,3 edge) was also performed.
Results: No reaction product was found in PMN and intact epithelium. Ce precipitations could be visualized on the free surface of the plasma membrane in epithelium of elongated rete ridges. Precipitation reaction was not scavenged by the addition of catalase (an inhibitor of H2O2). An ESI analysis shows the distribution of Ce elements clearly correspond with that of P elements.
Conclusion: Such findings support the concept that Ce deposits react with P residues of atrophic plasma membranes.