DAO 52:191-198 (2002)  -  doi:10.3354/dao052191

Exocrine pancreatic carcinogenesis in the guppy Poecilia reticulata

John W. Fournie1,*, William E. Hawkins2

1US Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Gulf Ecology Division, 1 Sabine Island Drive, Gulf Breeze, Florida 32561, USA
2Gulf Coast Research Laboratory, College of Marine Sciences, The University of Southern Mississippi, PO Box 7000, Ocean Springs, Mississippi 39564, USA

ABSTRACT: Exocrine pancreatic neoplasms developed in the guppy Poecilia reticulata following exposure to the direct-acting carcinogen methylazoxymethanol acetate (MAM-Ac). Fish 6 to 10 d old were exposed to nominal, non-toxic concentrations of 4 and 10 mg MAM-Ac l-1 for 2 h and then transferred to carcinogen-free water for grow-out. Whole specimens were sampled monthly up to 9 mo post-exposure to follow the histologic progression of the lesions. No neoplasms occurred in 119 control specimens examined. Pancreatic acinar cell adenomas and carcinomas occurred in 42 of 243 (17%) of the specimens exposed to MAM-Ac. As in earlier studies, specimens exposed to the low MAM-Ac concentration exhibited a higher pancreatic neoplasm incidence (27.8%) than those exposed to the high concentration (7.8%). Acinar cell adenomas accounted for 27 of the 42 neoplasms. Adenomas exhibited a high degree of acinar cell differentiation and some contained foci of atypical acinar cells that were less differentiated and more basophilic than were surrounding adenoma cells. Carcinomas occurred in 15 specimens and exhibited a range of cellular patterns. Although no distant metastases were found, carcinomas tended to invade neighboring tissues and organs. The occurrence of carcinogen-induced pancreatic neoplasms in guppies strengthens the usefulness of small fish species in carcinogen testing and provides an additional model for studying pancreatic neoplasia.


KEY WORDS: Fish · Exocrine pancreas · Neoplasia · Carcinogenesis · Guppy


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