The ultrastructure of the liver of the rainbow trout: normal structure and modifications after chronic administration of a polychlorinated biphenyl Aroclor 1254

Abstract

Rainbow trout (Salmo gairdneri) were fed dietary levels of 0-, 1-, 10-, and 100-ppm Aroclor 1254 for 229 to 330 days. The ultrastructural features of control livers were similar to those of other animals, but rainbow trout liver differed from mammalian liver in an apparent absence of Kupffer cells. Also small dense duct-type cells were present that formed a transition zone, combining with hepatocytes to form canaliculi; alone they formed preductules and in combination with cells of lower density they formed ductules. Microtubules were found in the vicinity of canaliculi and less frequently adjacent to the plasma membrane of other cell surfaces. They were not seen at the sinusoidal border as they are in mammalian liver. Peroxisomes lacked nucleoids. There were no ultrastructural liver changes in the 1-ppm group. The most frequently encountered alterations in both the 10- and 100-ppm groups were those involving the nucleus. These included irregular and bizarre nuclear outlines, separation of nucleolar components, and large nuclear pseudoinclusions. Other frequently encountered changes were slight increases in smooth endoplasmic reticulum, altered rough endoplasmic reticulum, increased lysosomes, reduced and altered glycogen, increased lipid, and hypoxic vacuoles. Seen also were concentric membrane arrays, myelin figures in intercellular spaces and Golgi cisternae, and bundles of fine tubules throughout the cytoplasm.