Electron microscopical study on the terminal secretory units of the labial salivary glands in patients with Sjögren's syndrome

Abstract

The ultrastructural changes in the terminal secretory units of the labial salivary glands, in which was demonstrated light microscopically the characteristic appearance of Sjogren's syndrome, were investigated in 12 cases. A small number of lymphocytes appeared interspersed in the dilated interepithelial spaces. Acinar cells showed regressive changes of various degrees, i. e. in the mature acinar cells the secretory granules were irregularly shaped and often found fused to each other while the intracytoplasmic organellae were swollen and destroyed in the immature acinar cells. These findings suggested that both the productive and secretory processes of the secretory granules in the acinar cells were disturbed. And finally the acinar cells appeared completely destroyed and their whole intracytoplasmic contents spilled into the acinar lumen. In some of the terminal units which consisted of immature acinar cells, the acinar cells were arranged irregularly and showed a syncytial appearance. This finding might suggest the socalled tubular metaplasia or canalicular regression. There was no regenerative appearance of the acinar cells. The myoepithelial cells, located in the basal portion of the acinar cells, were more resistant to the inflammatory changes than the acinar cells, however, pyknosis of the cytoplasm, formation of many thin cytoplasmic processes and increase in the number of pinocytotic vesiclae were found in the advanced stage. There were no proliferative changes in the myoepithelial cells.