Mechanical Properties of Human Membranous Labyrinths

A prototype of a tension testing machine capable of measuring microloads (“the microtension tester”) was developed to examine the mechanical properties of fine bio-membranes. The mechanical properties of the human membranous labyrinth were studied in two temporal bones from one human being. The test was carried out at room temperature in physiolocical salt solution. The tension rate was 1mm/min. The measurement was done on formalin fixed specimens, but on the basis of our findings reported recently on the mechanical properties of the semicircular canals of fish, frogs and guinea pigs, the results were converted into figures representing those of fresh tissue.In comparisons of tensile strength, saccular membrane was the weakest, followed by Reissner's membrane and utricular membrane, and semicircular canal membrane was the strongest. There was a good correlation between the thickness and the strength of the membrane.These findings suggest that the increase in endolymph volume or pressure takes place throughout the entire labyrinth in Meniere's disease, and because of the differences in the mechanical properties of the membranous labyrinth, endolymphatic hydrops occurs only in the cochlea and the saccule.