Functional thyroid tumors in the kidneys of platyfish.

presence of thyroidal tissues in places in the body far removed from the usual pharyngeal em bryonic source has often stimulated considerable speculation and discussion. For example, thyroidal follicles in the human ovary (struma ovarii) are believed by Means (5) to be local teratomatous tis sues, and not metastatic growths, benign or other TABLE 1 p Plus sign indicates that tumors are present but their frequencies have not been determined as yet. wise. In this report we propose to describe the oc currence of both normal and hyperplastic thy roidal tissue in fish organs as far anterior as the eye, and as far posterior as the kidney, spleen, and versity (NR163-208) and the laboratory facilities of the Amen can Museum of Natural History. intestine. These findings, which appear to imply an extraordinary mobility of thyroid tissue in normal and goitrous fish, are presented for both their in trinsic interest and their possible value in the in terpretation of atypically located thyroid tissue in man. When first noted in a number of genetic strains of the platyfish (Xiphophorus mactdatus), hyper plastic thyroidal tissue located in the kidney was described as a spontaneous kidney tumor (1). This atypical cell growth formed cysts and eventually caused the death of the affected fish. Further study disclosed that this hyperplastic tissue had the morphological and physiological properties of thyroidal tissue in both the normal and hyper plastic state. Autographs, with the use of radio active iodine, showed that the tissue of the kidney tumors was capable of metabolizing iodine and binding it to a protein in the same way as the tissue of the thyroid gland itself. The distribution and properties of the thyroid-like tissue in kidney and other sites are the subjects of this report. MATERIALS AND METHODS Flatyfish (Xiphophorus maculatna) of several genetic stocks were studied-(Table 1). The â€oedo mesticated†• strains were obtained from fish fan ciers who had bred them previously for 15 or more years. The â€oewild†• stocks were obtained by our expeditions to Central America in the years mdi cated in the table. Most stocks in our genetics lab oratory have been maintained by brother-sister matings. All the stocks have been inbred closely, but not necessarily by brother-sister matings. All these strains have been maintained in this labora tory under similar conditions (4). The tumor mci dence in the â€oeFury†• stock was determined from records kept on …