Pericytes in the Human Vocal Fold Mucosa.

1. The human vocal fold is a vibrating tissue and vascular structures in organs which have the capacity to vibrate require a specific structure suitable for vibration. 2. The structure of the blood vessels is unique at the vocal fold edge as a vibrating tissue, where only small vessels, including arterioles, venules, and capillaries, are present. The capillaries are distributed in the superficial layer of the lamina propria (Reinke's space). 3. The blood vessels enter the vocal fold edge from the anterior or posterior end of the membranous vocal fold and run essentially parallel to the vocal fold edge. 4. Many pericytes can be seen around the capillaries in the human vocal fold mucosa. The cell bodies of the pericytes attach to capillary endothelial cells, and the branching processes encircle the capillaries and attach to the capillary endothelial cells at the tips. The processes of pericytes are in close contact with endothelial cells, sharing a common basement membrane with them. The tips of the processes form intercellular tight junctions with endothelial cells. 5. The pericytes in the vocal fold mucosa appear to provide mechanical support and protection to the capillary walls, particularly during phonation. The pericytes also appear to regulate the diameter of the capillary during and after phonation. Pericytes are also thought to be critical cells in vascular biology and angiogenesis, especially in revascularization following vocal fold tissue injury. 6. At birth, pericytes have already encircled the capillaries in the newborn vocal fold mucosa. The pericytes appear ready to provide support and protection of the blood vessels just after birth. 7. Vascular structures and their permeability are related to the specific structures and specific diseases of the human vocal fold mucosa as a vibrating tissue.