Comparison of the methods of cathodoluminescence, electronprobe microanalysis, and calcium staining, applied to human aorta with isthmus stenosis

Electron probe x-ray microanalysis is a useful method for studying pathologic and age-related calcification mechanisms in the aorta and in muscular arteries by means of elemental anlysis in microareas. In the present investigation, this method was correlated with the histochemical alizarin-S-calcium staining and with cathodoluminescence analysis in the scanning electron microscope. Portions of the proximal region of a human aorta with isthmus stenosis were shock-frozen and sectioned in a cryostat. Serial sections were investigated by calcium staining, electron probe, and cathodoluminescence microanalysis. Using quantitative electron probe microanalysis of calcium and phosphorus, it was shown that the principal regions of calcium phosphate mineralization could be located using either alizarin-S staining or cathodoluminescence analysis. The advantage of the cathodoluminescence analysis is its higher lateral resolution compared with that of light microscopy, and the fact that no special staining is required. In addition, it was possible to obtain scanning images, thus providing additional information about the topology of the tissue surface, which is necessary to decide whether or not the section is suitable for microanalysis. Quantitative microanalysis is a valuable tool for basic research on calcified arteries. The results of the combined analysis in the proximal and distal regions as well as in the stenosis will be published in a later paper.