Reticular fibers in the vocal fold mucosa.

Light and electron microscopic investigations of the reticular fibers (RFs) in the vocal fold mucosa were carried out on excised human adult larynges. The results are summarized as follows. Reticular fibers were found in the superficial and intermediate layers of the lamina propria of the vocal fold mucosa. They were most abundantly discovered around the vocal fold edge, and they decreased toward the superior and inferior portions of the vocal folds. The RFs were composed of slender fibrils, about 40 nm in diameter, and having cross-bands with a periodicity of about 67 nm. They were found in close association with the basal lamina of the epithelium and blood vessels. The slender fibrils of the RFs did not form any bundles, but branched and anastomosed. The RFs formed delicate 3-dimensional networks, and the spaces among the fibers were relatively large. Glycoprotein and glycosaminoglycan (proteoglycan) were situated around the RFs and in the spaces among the fibers. Elastic fibers were located in the spaces among the RFs. The 3-dimensional structure of the RFs in the vocal fold mucosa, first demonstrated in this study, appears to be one of the key components of the structural maintenance and viscoelasticity of the vibrating vocal fold tissue.