A morphometric study of age-related changes in adult human epiglottis using quantitative digital analysis of cartilage calcification.

The epiglottis plays an important role in deglutition in humans. The present study investigated age-related changes in the epiglottis using macroscopic and microscopic measurements. Epiglottic specimens from 281 Japanese adult cadavers (177 males, 104 females) were obtained. Specimens were divided into three groups according to age: group I: 20-39 years old (32 males, 26 females), group II: 50-69 years old (82 males, 36 females), and group III: 80-98 years old (63 males, 42 females). Width, height, and thickness were measured macroscopically. To evaluate the degree of calcium deposition, the calcium volume in digitalized von Kossa-stained sections was assessed using a quantitative analysis. An elemental analysis of the area detected with von Kossa staining was done using energy-dispersive X-ray fluorescence spectrometer (EDX). Measurements of the thickness and cell density in the superficial and deep layers of epiglottic cartilage were performed in horizontal histological sections. No significant differences in macroscopic width or height were found across the age groups in either sex. A series of three measurements in males was significantly larger than in females (p<0.05). The volume of the calcium deposit area was greater in males than in females (p<0.05) and was significantly increased in group III in males (p<0.05). The lower level of the epiglottic cartilage showed a greater calcium deposit area than the upper level. In the scanning image by line and surface analysis using EDX, the calcium deposit areas detected with von Kossa staining indicated a close association of calcium and phosphorus ions. The mean Ca/P molar ratio in the calcium deposit area was 1.32+/-0.12. Microscopic cartilage thickness increased significantly with age (p<0.05), and was greater in males than in females (p<0.05). Cartilage cell density in the superficial cartilage layer was higher than in the deep layer and was decreased in group III (p<0.05). Cartilage cell density was lower in males compared to females. Diameter of chondrocytes significantly increased in group III (p<0.05) and was larger in males than in females in group III (p<0.05). Epiglottic cartilage exhibited marked sex-related differences and progression of calcification with age. Calcification of epiglottic cartilage in elderly individuals may affect movement patterns in deglutition.