Structural and functional aspects of rodent salivary glands including two desert species

Abstract

Abstract The submaxillary glands of the adult desert rat, antelope squirrel, rat, mouse and hamster have in common low levels of amylolytic enzyme in comparison with the relatively high levels of parotid gland amylase in these rodents. Submaxillary gland acini are classed as seromucous secreting although there is some variation in the carbohydrate histochemistry of these secreting units. Granular tubules are absent in antelope squirrel submaxillary glands and they are present in the submaxillary glands of the desert rat, rat, mouse and hamster. Electron micrographs reveal the presence of numerous basal folds in the acini of antelope squirrel submaxillary and parotid glands. These structures were not observed in the salivary gland acini of the hamster. Golgi membranes and “immature” secretion granules are topographically intimate in parotid glands of the hamster and antelope squirrel. In the submaxillary glands of these two rodents, the secretory material appears to originate in relation to the endoplasmic reticulum and secondarily, the granules become associated with a diffusely arranged system of Golgi membranes. The sublingual glands of all the rodents of this study are predominantly ones that produce mucous secretion and contain well developed striated duct systems. Of the salivary glands investigated in this study, the parotid glands of the rat, mouse and desert rat produce an isotonic saliva; the saliva of the other glands is definitely hypotonic.