Metabolic activity of cells in the macula flava of the human vocal fold from the aspect of mitochondrial microstructure

OBJECTIVES: There is growing evidence to suggest that the cells in the maculae flavae of the vocal fold mucosa are tissue stem cells of the human vocal fold. This study investigated the metabolic activity of the cells in the maculae flavae of the human vocal fold from the aspect of mitochondrial microstructure. STUDY DESIGN: Histologic analysis of the human vocal folds. METHODS: Five normal human adult vocal folds obtained from autopsy cases were investigated under transmission electron microscopy. RESULTS: Mitochondria were randomly distributed in the cytoplasm of the cells. The morphological features of the mitochondria consisted of a double‐membrane‐bounded body containing matrices and a system of cristae. In each mitochondria, the lamellar cristae were sparse. The intercristal space was occupied by a mitochondrial matrix which contained electron‐dense matrix granules, mitochondrial DNA, and ribonucleoprotein granules. Some mitochondria spread out over or fused to the surface of a lipid droplet in the cytoplasm. In addition, both the mitochondrial outer and inner membranes and the membranes of the lipid droplets had disappeared. Some close association between mitochondria and rough endoplasmic reticulum was present. CONCLUSIONS: The features of the mitochondria of the cells in the maculae flavae of the human vocal fold suggested that their metabolic activity and oxidative phosphorylation were low and that they may have shifted to the utilization of lipids to some extent for their metabolic needs. LEVEL OF EVIDENCE: NA