Morphological survey of teleost organs important in carcinogenesis with attention to fixation

Key features of the gross and microscopic anatomy of teleost liver, digestive tract, kidney, and skin were reviewed from the world literature. Illustrations of the above and new findings were obtained from light as well as scanning and transmission electron micrographs of tissues from 7 freshwater fish species: Alosa sapidissima, American shad; Esox lucius, northern pike; Lepomis macrochirus, bluegill sunfish; Pimephales promelas, fathead minnow; Stizostedion vitreum, walleye; Oryzias latipes, Japanese medaka; and Ictalurus nebulosus, brown bullhead catfish. Emphasis was placed on structural features that may influence interpretation of toxic and carcinogenic lesions. A discussion of fixation of small fish for light and electron microscopy and histochemistry is presented.