Scanning acoustic microscope (SAM) gives an image which reflects not only microstructure but also mechanical properties of the object. We have attempted to use SAM in investigating the mechanical properties of the vocal fold. This paper focuses on two aspects: preparation of specimens for SAM and hardness of the tissue components of the human vocal folds. Four fresh human vocal folds were used in this study. From each vocal fold, three kinds of specimens were prepared: a thick frozen section of 1mm in thickness, a thin frozen section of 10μm in thickness, and a paraffin-embedded section. Additional paraffin-embedded sections obtained from 5 larynges fixed in 10% formalin were also investigated. The results are as follows: 1. In order to investigate mechanical properties, such as elasticity and viscosity, of vocal fold tissue, thin and thick frozen sections are recommended. 2. Relative stiffness of different tissue components can be determined even with paraffin-embedded sections. 3. Among the tissue components investigated, the fibrous component was the hardest, the epithelium came next and the ground substance was the softest. 4. The hardness of each layer of the mucosa was in the following order: intermediate and deep layers of lamina propria>epithelium>superficial layer of lamina propria.
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