Fig. 7. Immunocytochemical analyses of V-H⁺ATPase and Na⁺K⁺-ATPase in cryosections of the branchial filaments of Riftia pachyptila. (A) Transverse section of branchial filament stained for V-H⁺ATPase. (B) Magnification of cell membrane area from A showing the apical localization of the V-H⁺ATPase (arrowheads). (C) Localization of Na⁺K⁺-ATPase in transversal section of branchial filament showing its basal localization in the epidermis (arrowhead). CF, coelomic fluid; C, cuticle. Scale bar, 40 µm (A,C); 10 µm (B).