INTRODUCTION: Hyaluronic acid (HA) plays an important role in mechanical stability, viscoelasticity, osmotic control, and regeneration of the extracellular matrix of the vocal folds; however, there are differences of opinion and conflicting results regarding concentrations of HA in individuals of different sexes and ages. OBJECTIVE: To evaluate HA concentration and distribution in the vocal folds of individuals of different sexes and ages. METHODS: A total of 51 vocal folds were removed during necropsy and divided into 3 groups: Group I (30-50 years; n = 15), Group II (60-75 years; n = 18), and Group III (≥76 years; n = 18). Histological slides were prepared for immunohistochemical analysis and incubated with anti-HA at a dilution of 1:800 and secondary antibody. Analyses of the histological slides were performed by a researcher blinded to the group allocation, and the density of brownish antibody in the lamina propria (superficial and deep layers) was determined in 3 non-overlapping areas μm2. RESULTS: With age, the HA concentration gradually increased in females in the superficial (18% vs. 28%) and deep layers (20% vs. 45%). In men, the HA concentration was decreased in the superficial layer (34% vs. 25%) and a considerable decrease in HA concentration was observed in the deep layer among those aged 60-75 years (? vs. 32%). The distribution of HA in both sexes followed the same linear concentration. CONCLUSIONS: The HA concentration decreases with aging in a homogeneous way, without differentiation of gender.
