Abstract
Purpose: :
Myoepithelial cells form a major population surrounding acini and intercalated ducts of exocrine glands and have a stellate, multiprocessed morphology. Their contraction may play a role in expelling the secretory products from glandular lumina into excretory ducts. However, little is known about the function of myoepithelial cells in human lacrimal gland. To explore one of the functions of myoepithelial cells in human lacrimal gland, age–related change of myoepithelial cells was examined.
Methods: :
Lacrimal gland tissues obtained from autopsies were cut into two portions, the palpebral and orbital lobes, then the fixed palpebral or orbital tissue was embedded in paraffin, and sectioned. Ten histologic–proven normal human lacrimal glands from young patients (young group, <50 years old, range:2–48) and 16 lacrimal glands from old patients (old group, >70 years old, range:71–87) were used in this study. Myoepithelial cells were immunohistochemically identified by anti–α–smooth muscle actin (SMA) antibody. In the respective palpebral and orbital lobe sections, the intensity of immunoreactivity was scored on 3–point scale: 1, weak; 2, moderate and 3, intense.
Results: :
SMA immunoreactivity scores were lower in the old group of the orbital lobes compared to the young group of the orbital lobes (Mann–Whitney U test, p<0.05). However, in the palpebral lobes, no statistical difference of the scores was observed between the young and old groups. Interestingly, in the sections with acinar atrophy in the old group, some of them showed the intense immunoreactivity of SMA, and some were weak.
Conclusions: :
The present results suggest that weak immunoreactivity of SMA found in the elderly patients may be related to a decline in tear film function associated with aging. Further studies will be needed to explore the relationship between the acinar atrophy and the function of myoepithelial cells.
Keywords: aging • lacrimal gland • pathology: human