Sex-related expression of sialic acid acceptor sugars in the mouse submandibular gland. Simultaneous visualization by confocal laser scanning microscopy

The novel combination of sialidase digestion with simultaneous PNA and DBA binding yielded marked differences on sialoglycoconjugate occurrence and distribution in the mouse submandibular gland acinar cells of the two sexes. Striking differences in the structure of terminal disaccharides within stored secretory sialoglycoconjugates were also found. High content of sialic acid, characterized by the terminal sequence sialic acid-alpha-N-acetylgalactosamine, was established to only occur in the male acini where secretory cells appeared to be differently stained; indeed, some cells exhibited codistribution of sialic acid-alpha-N-acetylgalactosamine and sialic acid-beta-galactose terminal disaccharides, whereas other ones exclusively contained one of the two kinds of terminal sequences. In the female acinar cells, the secretory products were found to be almost exclusively composed by glycoconjugates having sialic acid subtended to beta-galactose without appreciable differences between acinar cells. Our finding of such extensive differences in the acinar cells of male and female mice adds new insights into the submandibular gland sexual dimorphism, commonly attributed to the androgen responsiveness of the granular convoluted tubule portion of the gland