Fig. 9. TEM showing chloride cell ultrastructure in the filament epithelium of tilapia exposed to 45 g l^–1 and 55 g l^–1 salinity for 120 h. (A) Apical pit (A), formed by interdigitated apex of mature chloride cells (CC) and cytoplasmic projections of accessory cells (AC; asterisks), in fish exposed to 55 g l^–1 salinity; arrowheads, short junctions between CCs and ACs. (B) Mature chloride cell with a deeply indented nucleus. Scale bars: 1 µm.