Myoepithelial Cells (MEC) of the Salivary Glands in Health and Tumours.

Myoepithelial cells (MEC) are found in the secretory units of many mammalian exocrine glands such as mammary, sweat, lacrimal and salivary glands. They are interposed between the secretory cells and the basal lamina. Immunohistochemically they are found to contain keratin intermediate filaments and are, therefore, considered to have an epithelial origin but at the same time they contain a large number of myofilaments which represent a massive expression of contractile proteins such as actin, myosin, calponin and caldesmon. Thus have smooth muscle like property also and hence the name. Numerous functions of MEC have been described, the most important of them being important for contraction of the glands and recently it has been found to prevent tumour progression. It should be noted that the diversity in the occurrence and dilemma regarding the pathogenesis of salivary gland tumours is due to lack in uniformity regarding the cells participating in its oncogenesis, especially the MEC. Also proper and extensive studies regarding MEC are very limited and thus have posed difficulty for a pathologist to understand this cell. In this review we try to bring about a thorough description of this cell in both physiological and pathological aspects.