The myoepithelial cell: embryology, function, and proliferative aspects.

Myoepithelial cells form an integral part of the secretory and ductular portion of most glands. They share a common origin with lumenal epithelial cells and influence proliferation and differentiation of developing terminal glandular buds by producing a scaffold of basement membrane proteins. Their contractile capacity, controlled by hormonal and neural mechanisms, plays an important role in propulsion of secretions. Furthermore, myoepithelial cells maintain glandular structural integrity and transport metabolites to secretory cells. The advent of modern immunochemistry made identification of specific myoepithelial cell markers possible which facilitated studies on their presence and behavior in disease processes. Although the significance of many myoepithelial alterations is speculative, some have proved valuable in determining the histogenesis of glandular lesions.