Fig. 1. Confocal laser scanning micrographs of whole-mount preparations of gill filaments in killifish acclimated to defined freshwater with low- (A,D), mid- (B,E) and high- (C,D) NaCl. The gill filaments were stained with FITC-labeled anti-Na⁺, K⁺-ATPase. (D-F) Magnified views of a flat region of the afferent-vascular edge, where most branchial mitochondria-rich (MR) cells are distributed. Scale bars, 100 µm (A-C); 50 µm (D-F).