STRAINs OF PLATYFISH (Xiphophorv. maculates) USED IN KIDNEY

Received for publication October 2, 1954. 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.