Studies on the Transmissibility and Cytology of the Renal Carcinoma of Rana Pipiens.

SUMMARY The incidence of renal carcinoma in frogs maintained in the laboratory was not significantly affected by the inoculation of cell suspensions or cell-free filtrates of tumors. There was no significant difference in the tumor incidence in experimental or control frogs whether maintained individually or in groups of ten. Histological sections of 61 tumors stained with Feulgen and fast green revealed that there were two types, designated here as Types I and II. Type I tumors consisted of enlarged cells, the nuclei of which contained a large amount of intensely staining Feulgen-positive material. Mitotic activity was seen in every tumor of this type, and a spherical or oval, dense, Feulgen-positive body was observed in the cytoplasm of many of the cells. The cells of Type II tumors were also enlarged but appeared to be necrotic or de generating. The nuclei stained faintly with Feulgen, and the chromatin material was very sparse. Mitotic activity was rarely seen in these tumors. In every tumor of this type some cells exhibited an irregularly shaped nuclear aggregate which stained intensely with fast green. Of the 61 tumors examined histologically, 54 were Type I, and seven were Type II. All the Type I tumors were obtained from frogs that had been kept at 20°-25° C. since their arrival in the laboratory. All the Type II tumors were obtained from frogs which had been kept at 5° C. without being fed for at least 2 months (a state resem bling hibernation). The acidophilic nuclear aggregate which appears in Type II tumors was not observed in Type I tumors. The data which have been considered as evi-found that 21.3 per cent of frogs given inoculations dence that a virus is involved in the etiology of of desiccated or glycerinated preparations of tumor the renal adenocarcinoma of Rana pipiens stem tissue developed the tumor after 6 months of labo-from two main lines of investigation : studies of ratory maintenance, whereas 6.3 per cent of unin-transmissibility and of histology. Lücke(4, 5) oculated controls had the neoplasm. Duryee (1) * This investigation was carried out during the tenure of a observed a 17 per cent tumor incidence among predoctoral fellowshipfrom the Division of General Medical frogs given inoculations of filtrates of a series of Sciences,United States Public Health Service, and with sup-tumors, but the spontaneous occurrence of the port from U.S.Public Health ServiceTraining Grant No. 50aO. tumor in the frogs …