Glycoconjugate localization in larval and adult skin of the bullfrog, Rana catesbeiana: A lectin histochemical study

This study investigates whether or not the distribution of specific glycoconjugates within the skin is related to the regulation of water balance in the aquatic larvae and semiaquatic adults of the bullfrog, Rana catesbeiana. A lectin histochemical study was carried out on paraffin sections of dorsal and ventral skin from tadpoles in representative stages as well as from adult frogs. Sections were stained with the following horseradish peroxidase (HRP)‐conjugated lectins, which bind to specific terminal sugar residues of glycoconjugates: UEA 1 for α‐L‐fucose, SBA for N‐acetyl‐D‐galactosamine, WGA for N‐acetyl‐B‐D‐glucosamine, and PNA for β‐galactose. Results indicate that lectins serve as markers for specific skin components (e.g., a second ground substance layer within the dermis was revealed by positive UEA 1 staining). Moreover, each lectin has a specific binding pattern that is similar in dorsal and ventral skin; the larval patterns change as the skin undergoes extensive histological and physiological remodeling during metamorphic climax. These findings enhance our understanding of glycoconjugates and their relationship to skin structure and function—in particular, to the regulation of water balance in R. catesbeiana. J. Morphol. 261:184–195, 2004. © 2004 Wiley‐Liss, Inc.