THE FINE STRUCTURAL LOCALIZATION OF ALKALINE AND ACID PHOSPHATASE ACTIVITY IN THE RAT SUBMANDIBULAR GLAND

Abstract

The lead capture method was employed to study the fine structural localization of nonspecific phosphatase activity in the rat submandibular gland. Alkaline phosphatase activity was observed in association with the plasma membrane and pinocytotic vesicles of the myoepithelial cell. A polarity in the distribution of alkaline phosphatase activity was described along the myoepithelial cell process. More reaction product was observed in association with the plasma membrane on the parenchymal surface than on the plamsa membrane on the stromal surface, where reaction product was confined mostly to the pinocytotic vesicles. Activity was evenly distributed over both surfaces of the portion of the myoepithelial cell characterized by the nucleus. Activity was also observed to be associated with pinocytotic vesicles of the endothelial cells and the plasma membrane of erythrocytes. No activity was observed in association with the ductal elements. Acid phosphatase activity was associated with membrane-bound structures in the acini and ducts. These structures took the form of lipofuscin granules in the acini and either multivesicular or dense bodies in the ducts.