THE MYOEPITHELIAL AND BASAL CELLS OF DUCTS OF HUMAN MAJOR SALIVARY-GLANDS - A SEM STUDY

The cytoarchitecture and distribution of myoepithelial (mecs) and basal (bc) cells of intralobular (intercalated, striated) and interlobular (excretory) ducts of human major salivary glands were studied by SEM through a variety of maceration and microdissection techniques. Intercalated ducts are covered by mecs which, unlike the large stellate cells of acini, are spindle shaped. Small star shaped mecs are rarely observed even in the most distal striated ducts, while no such cells are seen in excretory ducts. Basal cells form a more or less continuous row of small, basally placed cells in excretory ducts. Sparse bc are occasionally present in proximal striated ducts as well. Following microdissection, bc exhibit a cup-shaped apex which embraces the convex base of principal cells. This configuration may explain why, in TEM, bc seem to possess lateral processes which may be mistaken for mecs processes. Moreover, the lateral surfaces of bc do not exhibit the complex system of plasmalemma folds typical of principal cells. The present study demonstrates that fusate mecs are present in intercalated ducts and that basal cells are distinct from myoepithelial cells. These results may have some relevance in histogenetic studies of salivary gland neoplasms.