Stellate cells in the human vocal fold.

Cells have been discovered that are star-like in appearance and that actively synthesize extracellular matrices in the human adult vocal fold mucosa. These cells have no nomenclature and are thus designated as vocal fold stellate cells (VFSC) in this study. Light and electron microscopic investigation of VFSC in the human vocal fold mucosa was carried out on excised human adult larynges. A comparison between VFSC and conventional fibroblasts was made. The results are summarized as follows. 1) The VFSC are distributed in human adult maculae flavae. 2) The VFSC are irregular and stellate in shape, possessing slender cytoplasmic processes. 3) Lipid droplets are present in the cytoplasm. 4) The VFSC have a small nucleus-cytoplasm ratio and well-developed rough endoplasmic reticulum, suggesting active protein synthesis in these cells. 5) No basal lamina is present, and filaments can be seen in the cytoplasm. 6) The VFSC show strong cytoplasm staining with periodic acid-Schiff stain and type III collagen. 7) The VFSC actively synthesize collagenous fibers, including reticular fibers, as well as other extracellular matrices, such as elastic fibers and glycosaminoglycan (hyaluronic acid). 8) The VFSC, first demonstrated in this study, actively synthesize extracellular matrices in the human adult vocal fold mucosa under normal conditions. 9) The VFSC participate in the metabolism of the extracellular matrices essential for the viscoelastic properties of the lamina propria of the human adult vocal fold mucosa as a vibrating tissue.