Research Product

In recent years, the use of freshwater and marine fishes in carcinogen research and in environmental carcinogen monitoring has grown substantially. Several advances must be made with selected species to make fishes advantageous and practical as assay subjects. Some of these advances should be (1) precise characterization of neoplastic endpoints and progression in experimentally exposed fishes, (2) abbreviation of length in time needed for risk evaluation of carcinogens or suspect agents in fishes, and (3) correlation of endpoints for carcinogen effects in fishes with those in other more-routine test species such as rodents (mammals). Because we believe that fishes, as a phyletic group, have much to teach us about neoplasia and environmental carcinogenesis, we are studying the experimental induction, progression, and fate of neoplasms in the liver of a marine coastal fish, the sheepshead minnow (Cyprinodon variegatus). The agent used to induce liver lesions in these studies was N-nitrosodiethylamine (DEN). The sheepshead minnow has been used for several years as a toxicological and carcinogen assay subject in our laboratories.5,6 The objectives of this study were to (1) characterize liver neoplastic development and (2) reduce or abbreviate times to endpoints in liver carcinogen assays using the sheepshead minnow with histological, ultrastructural, and enzyme histochemical endpoints.