Fig. 3. Representative photomicrographs of immunostaining for V-H⁺-ATPase in longitudinal sections of gill filaments from freshwater (A), seawater-acclimated (B) and seawater (C) Atlantic stingrays (x400). Scale bars, 100 µm. V-H⁺-ATPase-rich cells occurred on lamellae (finger-like projections) and/or interlamellar regions (basal to and between lamellae). Note the differences in abundance and distribution (lamella versus interlamellar region) of V-H⁺-ATPase-rich cells among groups.