LIVER MORPHOLOGY AND CYTOCHROME-P450 ACTIVITY IN FRY OF RAINBOW-TROUTAFTER MICROINJECTION OF LIPID-SOLUBLE XENOBIOTICS IN THE YOLK-SAC EMBRYOS

In this experimental study a microinjection technique for the administ ration of lipid-soluble xenobiotics in rainbow trout embryos was appli ed. One week prior to hatching, rainbow trout embryos were injected in the yolk-sac with commercial blends of polychlorinated biphenyls (PCB s), polychlorinated naphthalenes (PCNs), polychlorinated paraffins (PC Ps) and polybrominated diphenyl ethers (PBDEs). Six weeks later, the m orphology of the liver was examined, and the hepatic cytochrome P450-d ependent ethoxyresorufin-O-deethylase (EROD) activity was determined i n the swim-up fry. A dose-dependent induction of the EROD activity was found for the PCBs and the PCNs, indicating that application of the m icroinjection technique in fish embryo bioassays, combined with studie s of liver morphology and biochemistry, facilitate detection of biolog ical responses to certain lipid-soluble substances.