Unusual myoepithelium in the retrolingual salivary gland of the European hedgehog.

The myoepithelial cells of the hedgehog retrolingual salivary gland have an unusual three-dimensional configuration. Many of the myoepithelial processes are not closely apposed to the overlying epithelial cell, but pursue a seemingly independent course in the connective tissue. The multiplicity of myoepithelial processes gives the intercalated ducts the appearance of being ensheathed by several layers of smooth muscle, each delimited by basal lamina, but these layers can be traced back to their myoepithelial origin. Contiguous myoepithelial processes are joined to one another and to secretory or duct cells by desmosomes. Myoepithelial processes completely enclosed by a sleeve of basal lamina are attached to the lamina densa by numerous hemidesmosomes, ensuring that the processes and their covering move in concert during contraction and relaxation.