Mitotic proliferation of myoepithelial cells during regeneration of atrophied rat submandibular glands after duct ligation.

BACKGROUND

The purpose of the present study was to elucidate whether myoepithelial cells proliferate mitotically during regeneration of rat submandibular glands after atrophy.

METHODS

The excretory duct of the right submandibular gland of rats was doubly ligated near the hilum with metal clips, which were removed after 7 days of ligation (day 0). The regenerating right submandibular glands were removed from 0 to 14 days after removal of the clips. The removed tissue was examined with immunohistochemical double staining for proliferating cell nuclear antigen (PCNA) as a marker of proliferating cells and actin as a marker of myoepithelial cells, as well as with transmission electron microscopy (TEM).

RESULTS

The PCNA-positive myoepithelial cells were observed at the periphery of transitional duct-acinar structures, ducts and acini in the regenerating glands at every time-point, and the PCNA-labeling index of myoepithelial cells increased greatly especially between day 2 and 4. The mitosis of myoepithelial cell was also identified by TEM at day 4.

CONCLUSION

These findings suggest that myoepithelial cells are able to proliferate mitotically during regeneration of rat submandibular gland.