Ultrastructure of normal human parotid gland with special emphasis on myoepithelial distribution.

The myoepithelium in human parotid, unlike that in other species, is not limited to the acinar-intercalated ductal system but extends to the intra- and extralobular striated ducts. Myoepithelial cells of the striated ducts are smaller, fewer, and different in shape but they are similar in their relationships and ultrastructural morphology to the acinar-intercalated system. Distribution of myoepithelium is discussed with respect to its role and participation in the histogenesis of salivary gland tumours, especially those of intermediate and large duct cell origin.