A morphological study of age changes in adult human auricular cartilage with special emphasis on elastic fibers

Objective: It is well known that the size of the human auricle increases af ter it has finished development. The reason why the size of the human auric le continues to enlarge until advanced age after reaching adulthood was inv estigated by observation of the ultrastructure of elastic fibers in human a uricular cartilage. Methods: A total of 1958 subjects (966 males and 992 fe males) were classified into 18 age groups hom 0 to 5 years up to 85 years a nd above by 5-year intervals. Ear length, ear width, and length of ear atta chment were measured with calipers. Human auricular cartilage was obtained hom 26 subjects (16 males and 10 females) aged 14 to 79 years, stained by o rcein, and examined by light and electron microscopy, Results: Each item of measurement of human auricular size increased significantly with age in bo th males and females. On morphological examination by light and electron mi croscopy after orcein staining, elastic fibers in the cartilage were almost homogeneous in diameter and surrounded the cartilage lacuna in bundle-like fashion in young persons, whereas those in elderly persons were heterogene ous in thickness and had many fragments surrounding the territorial matrix In elderly persons, collagen-like fibers and small vesicles with heterogene ous electron density were frequently observed near elastic bundles around t he territorial matrix Conclusion: Structural changes of auricular cartilage associated with morphological age changes of elastic fibers may be one of the causes of expansion of the auricle after reaching adulthood.