X-Ray energy dispersive analysis and scanning electron microscopic study of normal and otosclerotic stapes with associated middle ear mucosa

ABSTRACT

A thorough description of ultrastructure of the normal stapes was required to determine changes associated with disease processes. In this work, the morphological appearance and mineral composition of normal and otosclerotic stapes were studied. In addition to the x-ray diffraction and x-ray micro-analysis, these methods allowed us to compare not only the morphology but also the mineral distribution in normal bone with that of otosclerotic lesions in order to gain some new insights into the disease process.12 human specimens [including the stapes with its associated mucosa] were studied. Six of them were normal fresh frozen, while the remaining were otosclerotic ones. The specimens were examined and photographed with Philips Scanning Electron Microscopy XL 3 at 30 kv. Also X-ray energy dispersive micro-analysis was performed with EDAX New XL-30 Zaphire equipment. In examination of the normal stapes, the surface architectural appearance of the human stapes appeared to have four different types of distinct patterns in all the specimens namely; honeycomb, fibrillar, dense and pitted. In the scanning electron microscope of the otosclerotic one, the four types' architectural appearance was not evident. There were two clearly differentiated zones corresponding to apparently normal bone and otosclerotic foci, with clear line of demarcation separating them. The apparently normal bone showed only a fibrillar structure with an irregular trabecular diagram on which rounded expansions were seen. However, in the otosclerotic plate zone even the fibrillar aspect disappeared. Disorganized collagen fibers surrounding holes with incomplete walls were seen. Next to the holes, there were patches of neo-bone formation appeared as abnormal irregular deposited Ca compounds, which seemed to be formed of irregular hydroxyl apatite crystals and rounded Ca deposits. Moreover, the analytic data of the otosclerotic stapes reflected lesser mineral components also the Ca/P ratio of the otosclerotic bone was [1.7] less then that of the normal bone [1.87]. That, perhaps might be attributed not only to the poor mineralization, but also to a changed mineral composition most probably, transformation of apatite into another calcium phosphate crystals. As regards the mucosal changes, this study revealed apparently marked decrease in the ciliated cells and multiple ulcers with loss of epithelial cells in otosclerotic specimens, which might be secondary to the capillary obstruction that also might be proved also by decrease in oxygen content found in the microanalysis technique. The gross morphology and transmission electron microscope did not clearly differentiate between the normal and the otosclerotic stapes, yet the scanning electron microscope and X ray microanalysis described many changes between them that might help clarifying some of the pathogenesis of otosclerosis