Liquid-diet-induced alterations of rat parotid acinar cells studied by electron microscopy and enzyme cytochemistry

Abstract

After 1 day on liquid diet, the acinar cells were filled with secretory granules, and gland amylase content was approx. 50 per cent greater than chow-fed controls. After 3 days, the number of secretory granules was reduced, and amylase levels had fallen to 50 per cent of controls. Altered or degenerating secretory granules and autophagic vacuoles containing rough endoplasmic reticulum, secretory granules and mitochondria were observed with increasing frequency during the 1st week. These structures were cytochemically reactive for trimetaphosphatase, a lysosomal hydrolase. Concomitantly, macrophages invaded the acinar parenchyma and phagocytosed the degenerating acinar cell components. Lipid droplets and large aggregates of glycogen particles were present in the acinar cells after 7–10 days. After 3 weeks, the acinar cells were considerably reduced in size and contained few secretory granules, but their structure appeared otherwise normal. These results indicate that the acinar-cell lysosomal system and invading macrophages, as in other experimental conditions, play an important role in the parotid-gland atrophy induced by liquid diet.