Fig. 1. Representative light micrographs of trout gills showing filament and lamellae from untreated (A,B), RU486-treated (C,D) and spironolactone-treated (E,F) fish acclimated to dechlorinated city-of-Ottawa tapwater (control; A,C,E) or artificial softwater (B,D,F) for 7 days. Chloride cells, which are densely stained, have proliferated over the entire surface of the gill epithelium of the softwater-acclimated fish, with the exception of those fish treated with spironolactone (F). Accompanying the chloride cell proliferation is an increase in lamellar thickness and a reduction in interlamellar distances. Chloride cells of fish acclimated to control conditions (A,C,E) and of spironolactone-treated fish acclimated to softwater (F) are smaller and far less numerous.
