Enzyme Histochemistry and its Application to the Study of the Mixed Tumors of the Salivary Glands

The activity of several hydrolytic (acid and alkaline phosphatase, ATP-ase) and oxidative (lactic, succinic, isocitric, glutamic, ((-glycerophosphate, glucose-6-phosphate and β-hydroxybutyrate dehydrogenases, NADH₂ and NADPH₂ tetrazolium reductases) enzymes has been studied using histochemical methods in four mixed tumors (pleomorphic adenomas) of human salivary glands: one of epithelial type, one of myxoid and chondroid type and two composed of patches of epithelial cells set in a myxoid stroma. Acid phosphatase showed little activity and alkaline phosphatase and ATP-ase none at all, either in the epithelial and in myxochondroid areas. However, epithelial areas contained clumps of cells strongly reactive for alkaline phosphatase and ATP-ase, sometimes arranged in a duct-like pattern around a homogeneous intercellular substance, also strongly reactive. Of the oxidative enzymes, NADH₂-diaphorase and lactic dehydrogenase were strongly active, NADPH₂-diaphorase and isocitric dehydrogenase were moderately so and the other dehydrogenases poorly active. There were no detectable differences in enzyme activity pattern between epithelial and myxoid or chondroid areas of the mixed tumors. In general the level of activity of the oxidative enzymes in the mixed tumors was intermediate between that of the acinar cells and that of the cells of the striated excretory ducts of the salivary glands.