CELL-PROLIFERATION ACTIVITY IN DUCT-LIGATED SUBMANDIBULAR-GLAND

Cellular proliferation activity in duct-ligated submandibular glands ( SMGs) of rats were evaluated by using index of proliferating cell nucl ear antigen (PCNA) immunostaining and H-3-thymidine incorporation. The normal SMGs showed a very low index (<0.1%) of PCNA immunostaining an d H-3-thymidine incorporation in the acinar and all the ductal segment s. On day 2 and 3 of duct ligation, index of PCNA staining and H-3-thy midine incorporation increased and reached a peak in degranulated gran ular convoluted tubules (GCTs), duct like structures (DLSs) and dilate d excretory ducts (EDs). On day 5 to 10. the glands showed fibrous pro liferation around the DLS, and cells in DLSs and dilated EDs had decre asing index of PCNA staining and H-3-thymidine incorporation. On day 1 4 and 21, the PCNA staining and H-3-thymidine incorporation had decrea sed and was mainly confined to the DLSs and basal cells of keratinizin g epithelial masses. In the unligated SMG of the opposite side of the duct-ligated animals, proliferating cells were found mainly in the aci nar compartment from the 2nd to 5th day of ligation. These results sug gested that in case of acceleration of secretry function of SMG, secre tory cells may proliferate as for the functional adaptation. However, in the case of obstructive lesions of SMG, GCT cells and ductal basal cells may have more potential for proliferation and these cells may be the major participant cells during glandular regeneration and possibl y in the histogenesis of the majority of salivary gland tumors, if not all.