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


Dr Shigeru Takahashi, Department of Oral Health Science, Hokkaido University Graduate School of Dental Medicine, Kita 13, Nishi 7, Kita-ku, Sapporo 060-8586, Japan. Tel./Fax: +81-11-706-4225. E-mail:


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.