Glycoconjugate Histochemistry in the Fundic Stomach and Small Intestine of the Frog (Rana ridibunda)

Abstract

Mucins in the fundic stomach and small intestine of Rana ridibunda were studied by using the techniques such as lectins as a specific probe binding terminal sugar residues and standard histochemistry in light microscopic level. In this study, we focused on morphofunctional diversities of different regions of the digestive tract and their feasible physiological and evolutionary implications. We used the following standard histochemical techniques: contained periodic acid-Schiff (PAS), Alcian blue (AB) pH 1.0 and 2.5, toluidin blue, aldehyde fucsin 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 neutral mucins and strongly sulphated acid mucins with α-N-acetyl-D-galactosamine and N-acetyl-β-D-glucosamine residues. Besides, the glycoconjugate secreted from the small intestine consists of mostly sulphated sialo and neutral mucins with N-acetyl-β-D-glucosamine moieties. It can be concluded that the differences in glycoconjugates types and the sugar residues in two digestive tract regions of Rana ridibunda may be related to special functions and rheological characteristics of the mucins.