A unique smooth muscle in salivary glands

―Structure and function of the myoepithelium―

Abstract

Abstract : Myoepithelial cells are the most unique smooth muscle and lie between the glandular epithelial cells and basal lamina of the secretory terminal portion of a variety of ecocrine glands including salivary, mammary, lacrimal and sweat glands. These myoepithelial cells have several characteristic features which differ from ordinary smooth muscle cells ; they are believed to be epithelial in origin and are usually stellate in form rather than simple spindle-shaped. The function of the myoepithelial cells are thought to be expelling the secretion from the secretory terminal portion to the duct by their contraction ability. They are also of particular importance in understanding the pathogenesis of the exocrine glands ; the involvement of myoepithelial cells in carcinogenesis has been indicated.

 The profile of myoepithelial cells varied considerably from gland to gland. This review is to introduce the fine and three-dimensional structures and functions of the myoepithelial cells in the salivary and several other exocrine glands which were elucidated by using immuno-histochemistry and scanning and transmission electron microscopy.