A cytochemical study on the salivary gland pleomorphic adenoma (mixed tumor) and the fetal and adult salivary gland.

We studied the pleomorphic adenoma of the salivary gland ultrastructurally and cytochemically [Mg2+-activated adenosine triphosphatase (Mg2+-ATPase)], compared it with normal human fetal and adult salivary glands, and evaluated the histogenesis of this tumor. In the adult salivary gland, reaction products shows Mg2+-ATPase activity were localized in the plasma membranes of myoepithelial cells adjacent to the acinar cells or intercalated duct cells. However, in the salivary gland of the 16-week fetus, they were seen along all adjoining plasma membranes of the cells of terminal buds and duct-like structures. The present case of pleomorphic adenoma comprised two histological components: solid and myxomatous areas. Reaction products were seen along adjoining plasma membranes of both light and dark cells in solid areas.