Ultrastructure and Histochemical Study of the Lingual Salivary Glands of Some Bird Species

Recent evidence supports the hypothesis that salivary glands develop independently of diet. However, histochemical features of the minor salivary glands appeared to be associated with the type of food ingested. We monitored ultrastructural and histochemical differences of lingual salivary glands among four species of birds, namely, Egretta ibis, Gallus gallus, Buteo buteo and Anser anser, by light and transmission electron microscopy. The respective diets of these species are very different. Periodic acid-Schiff reagent (PAS), alcian blue-PAS and bromophenol blue, and the carmine technique for neutral mucins were employed as the histochemical staining of the minor salivary glands of each species. The ultrastructure of secretory granules was heterogeneous and substructures were different among the four species. Histochemical analysis revealed the presence of sulfate groups and glycoconjugates, which appeared as the granules in these glands. These granules might represent of storage of secretory products that are located to the heterogeneous and complex ultrastructural patterns of granules in the mucous and seromucous cells.