Fig. 5. Representative high-magnification (x1000) photomicrographs of V-H+-ATPase-rich cells in gills from freshwater (A), seawater-acclimated (B), and seawater (C) Atlantic stingrays. Scale bars, 50 µm. Arrows indicate cells that best demonstrate the qualitative differences in staining observed among the groups. In freshwater stingrays, localization of V-H+-ATPase was diffuse throughout the cytoplasm and discrete along the basolateral plasma membrane of relatively large cells. In seawater-acclimated and seawater stingrayss V-H+-ATPase staining appeared to be stronger in the cytoplasm and less discrete along the basolateral membrane, relative to freshwater individuals. In all groups, no distinct staining was observed on the apical plasma membrane of V-H+-ATPase-rich cells.
