Glycoconjugate histochemistry in the fundic stomach andsmall intestine of the Frog (Rana ridibunda)

Abstract

Mucins in the fundic stomach and small intestine of Rana ridibunda were studied by using the techniques suchas lectins as a specific probe binding terminal sugar residues and standard histochemistry in light microscopiclevel. In this study, we focused on morphofunctional diversities of different regions of the digestive tract andtheir feasible physiological and evolutionary implications. We used the following standard histochemicaltechniques: contained periodic acid-Schiff (PAS), Alcian blue (AB) pH 1.0 and 2.5, toluidin blue, aldehydefucsin and bromfenol blue. For lectin histochemistry, five different lectins were used namely, DBA, WGA, PNA,ConA and UEA-I. The glycoconjugate produced in the fundic part of the stomach is composed of mainly neutralmucins and strongly sulphated acid mucins with α-N-acetyl-D-galactosamine and N-acetyl-β-D-glucosamineresidues. Besides, the glycoconjugate secreted from the small intestine consists of mostly sulphated sialo andneutral mucins with N-acetyl-β-D-glucosamine moieties. It can be concluded that the differences inglycoconjugates types and the sugar residues in two digestive tract regions of Rana ridibunda may be related tospecial functions and rheological characteristics of the mucins.