Sialoglycoconjugate dimorphism of the mouse submandibular gland acinar cells. Ultrastructural evidence by lectin-protein A-gold probes and sialidase digestion.

An ultrastructural analysis of lectin receptors on the submandibular glands from mice of both sexes was performed utilizing horseradish peroxidase-labelled lectins in conjunction with antiperoxidase antibody and protein A-gold. Both qualitative and quantitative sex-related differences in terminal sugar expression within secretory granules were detected. Following sialidase digestion, also subterminal acceptor sugars for terminal sialic acids, proved to be differentially expressed in the submandibular glands of males and females. Heterogeneous distribution of sialoglycoconjugates characterized by the terminal disaccharide sialic acid-beta-galactose was found to occur in female acinar cells. Also DBA reactive sites indicating the presence of terminal alpha-N-acetylgalactosamine discriminated between male and female acinar secretory glycoconjugates. This difference was emphasized by sialidase pretreatment that evidenced a marked occurrence of sialic acid subtended to alpha-N-acetylgalactosamine in males in contrast to a modest presence in females. The different sialylation patterns of acinar cell secretory products, probably related to a different expression of O- and N-linked sialoglycoconjugates, give insight into the sexual dimorphism of the mouse submandibular gland known until recently for the convoluted granular tubules.