Ultrastructure of the retrolingual salivary gland of the European hedgehog.

Retrolingual glands of the European hedgehog are pure mucous salivary glands consisting of mucous acini, intercalated ducts, and excretory ducts, but lacking striated ducts. The acinar cells, which lack basal folds, are filled with mucous droplets that have a fibrillogranular matrix. Many of the intercalated duct cells contain a single cytoplasmic inclusion that often is nearly as large as the nucleus. These inclusions are expanded cisternae of rough endoplasmic reticulum with moderately dense contents in which are embedded lamellar densities that give the inclusions the appearance of a badly reproduced fingerprint. Despite these obvious signs of secretory activity, the intercalated duct cells contain only a few secretory granules. Proceeding distally along the excretory ducts, the epithelium gradually changes from the simple cuboidal to simple columnar to pseudostratified. In those segments of the excretory duct composed of simple columnar epithelium, most cells contain small secretory granules. In the pseudostratified portion of the duct, the tall cells frequently contain an aggregate of mitochondria held together by regularly spaced filaments.