HISTOPATHOLOGICAL CHANGES OF THE GILLS INDUCED BY A GROUP OF AMPHOTERIC SURFACTANTS IN THE COMMON CARP

The histopathological effects of a homologous series of amphoteric sur factants, N-alkyl(C-8-C-18)-N,N-dimethyl-3-ammonio-1-propane sulfonate , on the gills of common carp Cyprinus carpio were examined by light m icroscopy. Fish were exposed to the lethal concentration (96-h LC(50)) of each surfactant for 96 h. The gills exposed to C-8 showed slight h ypertrophy of epithelial cells and epithelial lifting of the secondary lamellae. Marked epithelial lifting was observed after the exposure t o C-10. In the groups exposed to C-12, C-14, and C-16, hyperplasia bet ween the secondary lamellae occurred to such an extent that it led to lamellar fusion. In the gills exposed to C-18, hyperplasia was more ad vanced and revealed fusion of the primary lamellae. These findings sug gest that the extent of gill damage induced by this homologous series of amphoteric surfactants progressively deteriorated with the increase in the number of carbon atoms in the alkyl chain.