The change of myoepithelial cell after ligation and cut of submandibular gland duct in rabbit

Yun, Weon Suk; Kim, Chul Hwan; Kim, Kyung Wook

Abstract

Obstructive sialadenitis is one of common disease in salivary gland, and most common histologic features are loss of acinar cell and ductal dilatation associated with fibrosis, and infiltration of inflammatory cells. Although many experimental studies has been accomplished for the salivary acinar cell change in obstructive salivary gland disease, studies for myoepithelial cell were deficient. This study is designed for salivary gland tissue change, especially myoepithelial cell when nonspecific chronic sialadenitis or salivary duct injury by duct obstruction or cut can be occurred that is common encounted clinically. After ligation and cutting of submandibular gland of rabbit, groups of aminmal were sacrificed at 1, 2, 4 weeks postoperatively, submandibular gland were removed. The histopathologic evaluation was done with light microscopy. And, with immunohistochemical staining with alpha-smooth muscle actin, characteristics of myoepithelial cell were examined. With transmission electron microscopy, ultrastructure of myoepithelial cell were examined for distribution and ultrastructure of myoepithelial cell. The results were obtained as follows: 1. In the histopathologic evaluation, ligation and cutting group of 1 week, linkage of myoepithelial cell associated with acinar atrophy and degeneration were disappeared in both group. 2. More prominent squamous metaplasia was seen in acinar cells of ligation group of 2 weeks experimental rabbit than cutting group. 3. Acinar cells are nearly disappeared in both ligation and cutting group of 4 weeks, and myoepithelial cell also disappeared associated with acinar cell atrophy, and duct-like structure composed by squamous cells by squamous metaplasia in acinar cells were distributed. 4. In immunohistochemical study, both ligation and cutting group alpha-SMA distribution were diminished at 1 week experimental rabbits, but myoepithelial cell was more diminished in ligation group than cutting group, which were distributed around cells of squamous metaplasia. 5. Nuclear condensation, chromosome margination, and cytoplasmic vaculoation were appeared in myoepithelial cell of both cutting and ligation group after 1 week with transmission electron microscopy. But degenerative substance were seen in cytoplasm of myoepithelial cell of ligation group of 4 weeks. From the results obtained in this study, atrophy and degeneration of myoepithelial cell was more prominent in duct ligation group than duct cutting group, and myoepithelial cells were seen around cells squamous metaplasia of acinar cell.