Histochemical characterisation of carbohydrate residues during the morphogenesis of the urogenital system in Caretta caretta

Abstract

The distribution of carbohydrates in the urogenital system of Caretta caretta during embryogenesis and post-natal development was investigated by classical carbohydrate histochemical techniques and by the use of fluorescein-labelled lectins. PAS positive glycoconjugates were observed in nephrons of the mesonephros at an earlier stage of development than those from the metanephros. The lectin binding pattern of both kidney precursors revealed that the appearance of terminal carbohydrates in various parts of the nephron are dependent on the developmental stage of the animal. Binding sites for Wheat germ agglutinin and Maclura pomifera agglutinin were the most abundant throughout the developing kidney, whereas reactivity for Soy bean agglutinin and phythaemagglutinin was limited to fewer sites. The results indicate that the compartmentalised expression of cell glycoconjugates in the kidneys of juvenile Caretta caretta reflects the morphological and functional maturation of the nephron during development. Less pronounced lectin binding pattern of the gonad and genital ducts and the absence of changes during organogenesis indicate that terminal carbohydrates in the genital system of Caretta caretta do not play a major role in sexual differentiation.