HEPATIC ALTERATIONS AND INDUCTION OF MICRONUCLEI IN RAINBOW-TROUT (ONCORHYNCHUS-MYKISS) EXPOSED TO A TEXTILE-INDUSTRY EFFLUENT

Rainbow trout, Oncorhynchus mykiss, were exposed to a sublethal dose o f a wool shrinkproofing effluent for 15, 30, 45 and 60 days. Liver and blood samples were taken after the exposure time together with sample s of control handled fish. A light and electron microscope study was c arried out to evaluate the histopathological lesions induced in the li ver of treated fish. The genotoxic potential of the effluent was asses sed by piscine micronucleus test. Vacuolation of liver bile preductula r cells was observed in all exposed fish; abnormal lipid accumulation and basophilic foci were seen in the liver of one 30-days- and one 45- days-exposed fish, respectively. These specific alterations could be r elated to a pre-carcinogenic process. On the contrary, other lesions a lso described in all treated fish such as dilatation, vesiculation and degranulation of the rough endoplasmic reticulum, altered mitochondri a, increase in myelin bodies and lysosomes and presence of phagosomes in wandering macrophages might be considered as non-specific alteratio ns, similar to those described in fish exposed to different pollutants . Frequencies of micronucleated peripheral erythrocytes showed a signi ficant increase following 30-days exposure.