THE FINE STRUCTURE OF THE PAROTID SALIVARY GLAND OF THE DONKEY

The parotid salivary gland of the donkey was composed of pure serous acini. They were lined by pyramidal secretory cells, which were reacted negatively with PAS and alcian blue. The secretory cells which lacked the basal folds, possessed numerous granules which were the distinctive feature of the acinar cells. They appeared as homogenous electron dense substance surrounded by a rim of fine granular material. Abun dant RER cisternae, either in the form of parallel stacked cisternae infranuclearly located in cells containing few secretory granules or short and long cisternae among the numerous secretory granules, well developed Golgi-apparatus, numerous mitochondria, ribosomes and cytoplasmic filaments were observed. Steps of formation and development of these granules within the RER and Golgi-apparatus were recorded. The nuclei were large, slightly rounded somewhat basally located. The intercalated duct cells were pyramidal in shape. They were poor in organelles except of the numerous cytoplasmic filaments and mitochendria as well as few secretory granules. The striated duct cells did not possess the characteristic deep basal infoldings. They contained numerous rounded or oval shaped mitochondria mainly scattered around the nucleus in addition to the short RER cisternae, ribsomes and lipid droplets. The myoepithelial cells were found around the secretory acini as well as the intercalated duct, demonstrating the common feature of contractile cells.