Glycoconjugates in the chinchilla tubotympanum: A lectin histochemical study

Glycoconjugates are essential for normal functioning of the mucociliary defence system of the tubotympanum. Recently, terminal glycosylation sequences of glycoconjugates have been recognized for their role in mediating biological recognition, such as serving as a receptor for bacterial adherence. In this study, neuraminidase and 6 different lectins: Wheat germ agglutinin (WGA), Limax flavus agglutinin (LFA), Sambucus nigra agglutinin (SNA), Peanut agglutinin (PNA), Ricinus communis agglutinin-I (RCA-I), and Concanavalin A (Con A), were used to characterize histochemically the carbohydrate structures of glycoconjugates of the chinchilla tubotympanum. WGA, LFA, SNA, and RCA-I strongly labeled epithelial goblet cells, glandular mucous cells, cell surfaces, and mucous blanket. PNA weakly labeled only a small number of epithelial goblet cells and glandular mucous cells, and did not label cell surfaces. After neuraminidase treatment, PNA labeled large number of these secretory cells and cell surfaces. Con A predominantly labeled glandular serous cells, epithelial dark granulated cells, and cell surfaces, and also labeled dark cores of mucinous granules. These results revealed that: sialomucin are produced from glandular mucous cells and epithelial goblet cells and are present on cell surfaces and within the mucous blanket; their terminal trisaccharide linkage appears to be the sequence Neu5Ac (α2-6)Gal(β1-3)GalNAc and serum type glycoproteins are produced from glandular serous cells and dark cores of mucinous granules.