PRESENCE OF CARCINOEMBRYONIC ANTIGEN IN HEPATIC NEOPLASMS OF RIVULUS-OCELLATUS-MARMORATUS

Carcinoembryonic antigen (CEA), a glycoprotein, is found in the embryo nic gut and liver, and is in malignant neoplasms of the intestine and liver of humans. CEA is used as a diagnostic marker for liver and gut neoplasms. The objective of this preliminary study was to determine th e usefulness of CEA as a diagnostic marker in liver neoplasms of the m angrove rivulus, Rivulus ocellatus marmoratus, and to compare the resu lts to those reported in mammals. A commercially-available polyclonal antibody kit, Autoprobe III (Fisher Scientific, Houston, Texas), which utilizes avidin-biotin-peroxidase complex was used to stain CEA. Diet hylnitrosamine-induced neoplasms and control livers from a previous st udy were used. These paraffin sections were stored at room temperature for at least six years. Both Bouin's-fixed and formalin-fixed tissues were used. A positive control (1-day-old mangrove rivulus larvae), an d a negative control (omission of CEA antibody) were also used. CEA wa s found as red deposits in the gut mucosa, epidermis, and the brush bo arder and tubular epithelium of the kidney of the I-day-old-fish, cont rol fish and the fish that had liver neoplasms. No CEA was found in th e negative controls, the livers of postive controls and the normal adu lt livers. The liver tumors that had characteristics of biliary neopla sms stained positively for CEA, but the hepatocellular neoplasms were negative. The presence of CEA in the gut mucosa and the biliary neopla sms of fish is similar to the results of similar studies of human tiss ues.