[Age-dependent changes in the phosphorylation of nuclear phosphoproteins of rat salivary glands]

Age-related changes in cellular activity in human submandibular glands as evaluated by argyrophilic nucleolar organizer regions

OBJECTIVE

To examine the age-related changes in cellular activity of epithelial components of human submandibular glands, evaluated on the basis of argyrophilic nucleolar organizer regions (AgNORs).

DESIGN

Epithelial components of human submandibular glands were divided into serous acinar cells, mucous acinar cells, intercalated duct cells, striated duct cells, and interlobular duct cells. The mean AgNOR number of each cell type was compared among six age groups.

SETTING

The study was conducted at the Department of Oral Pathology, Tohoku University School of Dentistry, Japan.

SUBJECTS

Necropsy specimens from 66 males and 57 females 1 to 97 years old.

RESULTS

In all cell types except for intercalated duct cells, the mean AgNOR number was lowest in the 0-14 year-old group and highest in the 15-29 year-old group. The value then gradually decreased with advancing age and ultimately reached a similar level to that in the 0-14 year-old group. In intercalated duct cells, the mean AgNOR number did not differ significantly between any age group. There were no significant sex-related differences.

CONCLUSIONS

The cellular activity of almost all components of human submandibular glands rises in adolescence and young adulthood and then decreases with aging. These results suggest that intercalated duct cells are capable of not only proliferation but also division into other components; these cells may thus compensate for the reduced activity of other components in elderly subjects.