Elastic cartilage properties of the tip of the vocal process of the arytenoid cartilage

Objectives: This study aimed to investigate the histological and ultrastructural features of the elastic cartilage at the tip of the vocal process in the arytenoid cartilage, which is essential for laryngeal biomechanics.

Methods: Five larynges, including the vocal folds and epiglottis, were examined using transmission electron microscopy. The elastic cartilage at the tip of the vocal process was compared to the epiglottic cartilage within the same larynx to elucidate structural differences.

Results: The elastic cartilage at the vocal process tip consisted of chondrocytes, elastic fibers, collagen fibrils, and ground substances. Chondrocytes in the vocal process were smaller and not distinctly isolated in cartilage cavities (lacunae), unlike those in the epiglottis. Cytoplasmic analysis showed abundant free ribosomes and well-developed granular endoplasmic reticula, often with dilated cisternae. Amorphous materials were synthesized at the periphery of the cytoplasm and secreted through vesicles. The cartilage matrices were composed of elastic fibers, collagen fibrils, microfibrils, and proteoglycans. The density of elastic fibers was notably higher where elaunin fibers predominated. Collagen fibrils were thin, randomly oriented, and did not form thick bundles. Microfibrils formed delicate three-dimensional networks with other extracellular matrix components. And proteoglycan granules were located in the interstitial spaces among other cartilage matrix components and attached to them.

Conclusions: The unique structural features of the elastic cartilage at the tip of vocal process, when compared to the epiglottic cartilage, suggest a specialized functional role in maintaining the flexibility and resilience required for vocal fold adduction and abduction during phonation and other laryngeal functions.Level of evidence: NA.