Histologic Changes In Damaged Submandibular Gland Of SD Rat

[Objective] To establish damage submandibular gland model of SD rat by main secretory duct ligation, we checked the histologic changes of damaged gland before and after reopening of the obstructed duct. [ Methods ] Thirty male Sprague-Dawlye (SD) rats of 10-weeks-old were used as sample. The duct ligation group were 20, the reopening of the obstructed duct group were 10. Under anesthesia, the glands of duct ligation and theircontrol glands in the same rats (other side) were harvested in 3^rd, 6^th......27^th, 30^th dayrespectively. The glands that were reopened after obstructed duct for six days were gained in the 4^th, 5^th, 6^th, 12^th, 24^th day respectively. All glands were fixed in 10% formalin (pH7.2-7.4) solution. These slices were stained with Hematoxylin eosin (HE), AB-PAS of glycogen and immunohistochemical staining of Cytokeratin 19,α-SMA, Laminin, AQP-5. [ Results ]1. Morphology observation ,Compared with the control glands, the glands volume of duct ligation decreased gradually. The gland shape of duct ligation changed from egg-like to spindle-like. In the 6^th day, the gland volume of the reopening of the obstructed duct changed little. The color was slightly rosy. Peripheral vascular gradually faded after the duct opened. 2. Histological observation, HE, AB-PAS and immunohistochemical staining: Under the light microscope, mature acinars and granular duct can be observed. After duct ligation, acinar cells disappear and proliferation of duct epithelium occurs. The duct expressed CK19. In the basement membrane of duct, there were a layer cells that express LN andα-SMA, but not CK19. The great changes were found in the 12th day, and began to reduce from the 15th day. Reopening of the obstructed duct leads to repopulation of acinar cells. The cells expressed AQP5 gradually in the first five days. A large of mature acinar were found on 24th day. And a part of the duct cells differentiated into mature acinar ceils. In the same time, the expression of LN andα-SMA reduced gradually in the basement membrane of duct. [Conclusion] 1. After duct ligation, the volume of damaged gland was reduced, acinar cells disappear and proliferation of duct epithelium occurs. Reopening of the obstructed duct leads to repopulation of acinar cells. 2. During this regeneration process, the duct cells proliferate and differentiate into acinar cells within six days after reopening the duct. We presumed that intercalated duct cells may be precursors of both duct epithelial and acinar cells.