Chloride cell apical surface changes in gill epithelia of the armoured catfish Hypostomus plecostomus during exposure to distilled water

Armoured catfish Hypostomus plecostomus were exposed to distilled water for 15 days. High chloride cell proliferation occurred on the filament and lamellar gill epithelia. The apical surface of the chloride cells (66% of cells in both epithelia) showed significant reduction in the aquatic environment which was characterized by the development of a sponge-like organization. The chloride cell response suggests that these features could create a microenvironment which may favour either the reduction of ion loss or ion uptake in a environment characterized by an absence of ions.