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UNUSUAL FINDINGS IN ZEBRAFISH, DANIO RERIO, FROM TOXICOLOGICAL STUDIES AND THE ZEBRAFISH INTERNATIONAL RESOURCE CENTER DIAGNOSTIC SERVICE
Citation:
Fournie, J W., Kent, J. M. Spitsbergen, AND L A. Courtney. UNUSUAL FINDINGS IN ZEBRAFISH, DANIO RERIO, FROM TOXICOLOGICAL STUDIES AND THE ZEBRAFISH INTERNATIONAL RESOURCE CENTER DIAGNOSTIC SERVICE. Presented at 26th Annual AFS-FHS Meeting and the 44th Annual Western Fish Disease Workshop, Seattle, WA, Jul 15-17, 2003.
Description:
A number of interesting and unusual lesions have been diagnosed in zebrafish that have been evaluated from toxicological studies or submitted as cases to the Diagnostic Service at Oregon State University. Lesions were observed in various wild-type and mutant lines of zebrafish and included rare neoplasms such as ultimobranchial, excocrine pancreatic, and thyroid neoplasms. The zebrafish is the only fish species known to develop ultimobranchial gland neoplasms and the incidence of these lesions increases substantially in fish over 1.5 years of age. Both adenomas and carcinomas of the ultimobranchial gland were observed and the affected glands may be enlarged up to 50X normal. Exocrine pancreatic tumors included acinar cell adenomas, acinar cell carcinomas, and ductal adenocarcinomas. These neoplasms were also relatively large, reaching up to 4.0 mm in greatest dimension. The zebrafish pancreatic tumors displayed many similarities to those reported from other small fish species. The only thyroid neoplasms we have seen are follicular cell carcinomas. One of these lesions was a 4.5 mm mass in the branchial chamber. It was a poorly differentiated lesion that exhibited a solid growth pattern, and constituent cells exhibited cellular pleomorphism and nuclear atypia. All of these lesions will be illustrated, and differential diagnoses and possible causes will be discussed.