Fig. 5. X-Y projection images of immunofluorescence staining for Na⁺/K⁺-ATPase, Na⁺/K⁺/2Cl^- cotransporter (NKCC) and cystic fibrosis transmembrane conductance regulator (CFTR), at 0 h (A-D), 24 h (E-H) and 72 h (I-L) of the freshwater-to-seawater transfer experiment, and at 0 h (M-P), 24 h (Q-T) and 72 h (U-X) of the seawater-to-freshwater transfer experiment. Arrowheads and arrows indicate apical NKCC staining and apical CFTR staining, respectively. I, type-I cell; II, type-II cell; III, type-III cell; IV, type-IV cell. Scale bar, 10 µm.