Polarization of plasma membrane glycoconjugates in amphibian epidermis during metamorphosis

Wheat germ agglutinin (WGA) binding sites have been examined in tadpole epidermal cells at the level of both light and electron microscopy using the WGA-ovomucoid-gold technique. In premetamorphic tadpoles the reaction was observed on the plasma membranes of epithelial cells showing a gradient from inner to outer membranes. These glycoconjugates were polarized during development, and at the end of metamorphic climax they were only located in plasma membranes of stratum corneum. The existence of an apical cell surface coat is needed to facilitate the absorption of water through the adult epidermis. The possible implications of this polarization process are discussed.