On the histo-morphological changes of transplantable tumors.

1. When chicken sarcoma virus is serially inoculated on the mouse brain, it loses its carcinogenecity, but when it is inoculated on young chicken, granuloma develops in the liver and lung. When this granuloma is transplanted on adult chicken, a transplantable fibrosarcoma is obtained. 2. According to literature, the originaltumor of the Brown-Pearce cancer is a basal cell cancer, but that imported to Japan in 1953 presented a histological picture of carcinosarcoma. The metastasized tumor of the eye presents a purely cancer tissue, but when this is inoculated on the testis, carcinosarcoma is reproduced. It is therefore considered that the mother cell of the sarcoma is of host origin. 3. MY sarcoma is not a sarcoma, but is a spindle cell cancer. It might be a sarcoma which transformed into a cancer during serial transplantation, but perhaps it was originally a cancer but had been erroneously diagnosed as sarcoma. 4. The tumors we obtained by means of the feeding tests of Yoshida tumor all developed at organs other than those of the digestive tract. They are chiefly reticulo-sarcoma, but others which develop are malignant granuloma in the liver and lung, malignant adenoma in the kidney, papilloma of pelvis, and ependymoma in the cerebral ventricle. Since the discovery of the Yoshida tumor in 1943, serial transplantation has been conducted for 19 years with this tumor not only in Japan but also in foreign countries, but there has been no report to this date that a transformed strain has developed by cell transplantation. It therefore must be considered that the carcinogenesis observed in our feeding tests is a carcinogenesis due to a mechanism completely unlike that of cell transplantation. It has been confirmed by electron microscopy that in the early stage of transplantation of this tumor into the abdominal cavity there was an additional tumor growth due to the anaplastic proliferation of serous cells. 5. During the serial transplantation of viral tumors and/or virus dependent tumors, the tumor sometimes undergoes a morphological change. Though the cause of this is not yet sufficiently elucidated, it is suspected that there is some relationship with virus in the wide sense.