Histochemical characterization of carbohydrate residues during the morphogenesis of gastrointestinal and respiratory systems of Caretta caretta

Abstract

The distribution of carbohydrates in the gastrointestinal and respiratory tract of Caretta caretta during embryogenesis and postnatal development was investigated by histological and histochemical techniques and using fluorescein-labelled lectins. The results indicate that the compartmentalised expression of glycoconjugates found in the juvenile Caretta caretta is acquired during development. The occurrence of neutral carbohydrates in cells and extracellular matrix was dependent on the developmental stage of the animal. In general, periodic acid Schiff positive glycoconjugates of the respiratory tract occurred at an earlier stage of development than those from the gastrointestinal system. The lectin binding pattern of both organ systems revealed a more refined pattern of the types of carbohydrates present during development. Wheat germ agglutinin showed the broadest binding pattern, whereas Soy bean agglutinin and phythaemagglutinin were more limited in their binding to tissue structures. The terminal carbohydrates detected in the gastrointestinal and respiratory tract of Caretta caretta were similar to those observed in mammals; this finding emphasises the suitability of Caretta caretta as a model system for amniote development.