Scanning electron microscopic study of the human auditory ossicles

The human mallei, incudes and stapedes from 34 cadavers were examined using scanning electron microscope (SEM) to compare the bone surface type among different regions of auditory ossicles for males and females. On the malleus of both males and females, almost all of the surfaces showed a smooth fibrous appearance, characteristic of resting surface. Limited bone-forming or resorbing surfaces were identified on the malleus. As compared with the malleus, the percentage area of the resorbing surface and the vascular canal openings were higher on the incus and stapes, especially on the long process (Crus longum) of the incus and the neck of the stapes for both males and females. The percentage area occupied by the resorbing surface of the long process of the incus and the neck of the stapes correlated with that of the vascular canal openings. We consider that the malleus maintained the stable condition, while the long process of the incus and the neck of the stapes demonstrated marked bone resorption. We suppose that the bone erosion may be related to the vascularization in these regions. Though the percentage area of the resorbing surface and the vascular canal openings had the tendency to be high in females, we did not find any significant differences between the males and females. There was no significant correlation between the age and the area of resorbing surface or vascular canal openings.