Abstract
We attempted to clarify the genesis and microstructure of the annular ligament in human stapes with a transmission electron microscope and a scanning electron microscope. Experiment material specimens were prepared by excising temporal bones from cadavers. Target regions were then prefixed and excised, including the stapes and fenestra vestibuli from human embryos (at weeks 10, 13, 15, 18, 20, 24, and 28), adults (40-50 years) and the elderly (60-75 years). Results were follows: 1) Fine collagenous fibers of the S-V joint were observed for the first time at 10 embryonal week. and elastic fibers for the first time at 13 embryonal week. 2) Fibroblast cell density in the S-V joint declined in proportion to genesis progression. Distribution of the fibrous component of the S-V joint in adults was the greatest directly under the mesothelial cell layer and less in the middle layer. 3) It was assumed that between 24 and 28 embryonal weeks that the structure of the S-V joint reached its adult state. 4) Observation of the site linking the fibrous bundle to the marginal cartilage suggested that linkage would be more solid in the elastic fibers than in the collagenous ones. 5) As age increased, collagenous fiber volume tended to increase and fibrous bundle course to become more irregular.
