Evolution of Sarcoma 37 in cf1 Rats. Biological Aspects of the Spontaneous Cure of Tumors Studied After Irradiation and Administration of Immune Serum. Evolucao Do Sarcoma 37 Em Muganhos cf1. Aspectos Biologicos Da Cura Espontianea Do Tumor Estudados Apos Irradiacao E Administracao De Soro Imune

Transplants of sarcoma 37 were studied in regard to spontaneous regression of the tumor after irradiation and after the administration of immune serum. The following results were obtained: 1. Of 809 animals, 99% developed the tumor after transplantation; 2. The number of cells transplanted did not influence the growth rate, the percentage of spontaneous regressions, or the life spans of the animals; 3. Reimplantation of the tumor into mice which had previously rejected the tumor resulted in very few successful transplants; 4. The resistance of these mice to further attempts at implantation could not be altered by previous irradiation; 5. Animals transplanted for the first time suffer a faster evolution of the tumor, shortened life span, and a diminution of spontaneous regressions if they have been irradiated prior to transplantation (400r whole body); and, 6. Resistance to tumor growth could not be transferred passively in serum of mice which had rejected the tumor