A Histological and Three-Dimensional Reconstructive Study on Human Parotid Gland During Aging

Morphological changes of the human parotid gland during aging were investigated. The residual rate of acini was measured in 61 normal parotid samples obtained during surgery of the parotid gland tumors or other head and neck tumors. Mutual correlation between aging and residual rate of acini was observed in both female and male subjects. Female subjects showed a higher coefficient of correlation. Furthermore, 198 out of 224 patients complaining of xerostomiasis were female. These data suggest that the production and/or release of saliva is related to sex hormones. Three-dimensional reconstructions were performed in the following subjects: 34-year-old female, 67-year-old female and 80-year-old male. They showed the image of branching ducts and the increase of adipose tissues due to the atrophy of acini. An ultrastructural study revealed that lipid and lipofuscin granules were marked in the acinus and ductal cells of aged subjects. However, some subjects of advanced age with marked atrophy of acini retained normal secretory granules in the acinar cells, not complaining of xerostomiasis clinically. These findings indicate that remaining acinar cells are capable of producing sufficient saliva