Background: The larynx is a complex organ composed of different connective tissue elements. So far, the extracellular matrix of the larynx has not been thoroughly described. Hyaluronan is a matrix polysaccharide with physicochemical effects and biological cell functions in soft connective tissues.
Methods: The histochemical distribution of hyaluronan (hyaluronic acid, hyaluronate) was studied in tissue sections from various levels of the rabbit larynx by means of a hyaluronan-binding protein and avidin biotin peroxidase staining. Microwave-aided fixation was used to retain the extracellular location of hyaluronan.
Results: Hyaluronan accumulated chiefly in the subepithelial lamina propria and in the connective tissue enclosing striated muscle fibres of the thyroarytenoid muscle and vocalis muscle. This localization contrasted sharply with the weak staining for hyaluronan in muscles external to the thyroid cartilage. Intensive staining for hyaluronan was found in perivascular and periglandular connective tissue, as in the vacuoles of the hyaline cartilage of the thyroid, cricoid and arytenoid cartilages, and to a lesser extent in the lacunae of the chondrocytes and in the perichondrium of the elastic cartilage of the epiglottis.
Conclusions: Hyaluronan was heterogenously distributed in the rabbit larynx. It was abundant in intrinsic laryngeal muscles performing small, precise, and rapid movements and in the subepithelium at the glottic level, where it may facilitate mucosal movements. The abundant hyaluronan in the subglottic region may be involved in the control of vascular leakage and edema formation.