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RESEARCH PRODUCT

Sex-specific reaction of liver ultrastructure in zebra fish (Brachydanio rerio) after prolonged sublethal exposure to 4-nitrophenol

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Abstract Morphological alterations of the liver of zebra fish ( Brachydanio rerio ) following prolonged exposure to 0.1, 1 and 5 mg · l −1 4-nitrophenol (4-NP) were investigated by means of light and electron microscopy. Based on marked sexual dimorphism in control animals, liver recactions were both sex- and dose-dependent. Whereas at 0.1 mg·1 −1 only minor changes could be revealed, there were numerous structural modifications at 1 mg·1 −1 : Whereas male fish primarily react with a proliferation of smooth endoplasmic reticulum, female fish display a high degree of fenetrastion within cisternate of the rough endoplasmic reticulum. Both sexes exhibit infiltration of macrophages and lymphocytes, an increase in the number of binucleate cells, of lysosomes, autophagosomes and myelinated bodies, but a depletion of hepatic glycogen. At 5 mg·1 −1 , deformations of the nuclear membrane and partial lysis of mitochondria could be observed. At 1 and 5 mg·1 −1 4-NP about 25% of the animals investigated showed symptoms of degenerative transformations of the liver tissue into huge multinucleate cell masses with completely different ultrastructure. The evaluation of the results leads us to the conclusion that for toxicological studies on the effects of ‘priority pollutants’ histological and cytological investigations should be incorporated into an integrated methodological scheme.