Myoepithelial cells in the exorbital lacrimal and parotid glands of the rat in frozen‐etched replicas

Light and electron microscopy were combined with the technique of freeze‐etch to study myoepithelial cells. Myoepithelial cells of the rat exorbital lacrimal and parotid glands are found in relation both to secretory units and intercalated ducts. They lie within the basal laminae of secretory acini and intercalated ducts and do not protrude from the external surface. The myoepithelial cell consists of a central nucleus and surrounding cytoplasm with several cytoplasmic arms, the arms being less numerous in those cells associated with the ducts. The cytoplasm is filled with fine fibrils in parallel array. The interrelationship between myoepithelial cells and acinar or ductal cells is described with the aid of frozen‐etched replicas and the nature of the membrane surfaces is discussed. It is concluded that myoepithelial cells are contractile; their resemblance to smooth muscle is noted.