Lectin histochemistry of the submandibular and sublingual salivary glands in rats

Tissue sections from rat submandibular and sublingual glands were studied with lectin probes to identify terminal sugars of the glycoconjugates in various cell types of the salivary glands. The lectins used in the study were Canavalia ensiformis (Con A), Triticum vulgaris (WGA), Succinyl WGA (S-WGA) Ricinus communis I (RCA-I), Arachis hypogaea (PNA), and Ulex europeaus (UEA-I). The cytoplasm and cell membrane of both the serous and mucous acinar cells present high similarity in the distribution of some sugar residues, but differ considerably in the expression of specific sugars which appear either in the serous or in the mucous cells. The cytoplasm and cell membrane of the serous and mucous acinar cells express Mannose (Man) and Glucose (Glc), but lack Galactose (Gal), and N-acetylgalactosamine (GalNAc). Fucose (Fuc) is present only in the mucous acinar cytoplasm. The moderate to intense binding of WGA to the acinar and ductal cells and the lack of binding of S-WGA, indicate the presence of sialic acid rather than N-acetylglucosamine (GlcNAc). These sialic acid residues are not associated with PNA-binding sugar sequences as pretreatment with neuraminidase is not associated with exposure of additional PNA receptors.