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Acute Exposure of Medaka to Carcinogens: An Ultrastructural, Cytochemical and Morphometric Analysis of Liver and Kidney.

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Annual rept.1 Feb 1991-31 Jan 1992,

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This investigation is designed to determine the ultrastructural effects of diethylnitrosamine DENA and trichloroethylene TCE on hepatic and renal tissues of the Japanese medaka, Oryzias latipes. Another objective of the study is to ascertain whether DENA can function as an inducer of cellular transformation for TCE. One group of 60 medaka was exposed to DENA 10mgL for 48hrs, rinsed and maintained in fresh water. Another group of fish was exposed continuously to TCE 10mgL until sacrificed at one of the scheduled time points. A third group was exposed to DENA 10mgL for 48hrs, rinsed in fresh water and subsequently exposed continuously to TCE 10mgL until the time of sacrifice. A control group of medaka was maintained in fresh water. The sacrifices were conducted at 8, 16, 32, and 52 weeks subsequent to the initial exposure to DENA. All tissues have been processed according to the appropriate procedures. Tissue samples from TCEDENA exposed animals representing week 32 have been examined by transmission electron microscopy. Liver and kidney from control medaka have been examined and photographed, but will not be described in this abstract. While the majority of parenchymal cells observed from fish exposed to TCEDENA displayed no discernible effects of exposure, isolated hepatocytes and focal sites of cellular clusters were characterized by specific indicators of cytotoxicity. Livers from three fish were distinguished by the presence of multilocular cyst-like lesions that resemble spongiosis hepatis. Peroxisomes of hepatocytes were successfully marked by the cytochemical procedures selected for the study. Several of the examined kidneys displayed features of pronounced cytotoxicity predominately in

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  • Toxicology
  • Water Pollution and Control

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