Ultrastructure and histochemistry of the submandibular gland of the Japanese wood mouse (Apodemus ainu ainu Tokuda).

The submandibular glands of adult female and male Japanese wood mice (Apodemus ainu ainu Tokuda) were studied histochemically using toluidine blue (pH 2.5, 4.1 and 7.0, McIlvaine), PAS reaction, Millon's reaction for tyrosine, p-dimethylaminobenzaldehyde for tryptophan, and substrate film techniques for amylase and protease. The glands were also examined ultrastructurally and ultracytochemically by the periodic acid-thiocarbohydrazide-silver proteinate technique (PA-TCH-SP staining) for glycoprotein. The submandibular gland consisted of the striated ducts (SDs), the convoluted granular tubules (CGTs), the intercalated ducts and the terminal portions. In both sexes the acinar cells were seromucous in secretory nature, and the secretory granules contained glycoproteins and were negative to amylase and protease activities. By the PA-TCH-SP staining, the distribution of glycoproteins and fine structural alternations corresponding to the maturation of the secretory granules were demonstrated. The granules of the CGT cells contained tryptophan, tyrosine and neutral mucopolysaccharides. The granules showed negative reactions to acid mucopolysaccharides, protease and amylase activities, and glycoproteins. Glycogen particles in the apocrine processes were intensely positive to PA-TCH-SP staining. Dark and clear cells were distinguished in the SDs. The apical cytoplasm of the SD cells contained two types of vesicles. One type may represent reabsorption vesicles and the other secretory vesicles. Some of the SD cells had both microvilli, associated with reabsorption vesicles and apocrine process containing abundant glycogen particles on their luminal surface. From the statistical analysis of the average values, the CGT diameter of the male mice was significantly larger than that of the female mice.