Metastasis formation of Yoshida sarcoma heterotransplanted in adult golden hamsters treated with anti-hamster thymocyte serum.

Growth of Yoshida sarcoma cells heterotransplanted in adult golden hamsters treated with antithymocyte serum was investigated. Control animals were grafted with or without hydrocoritisone conditioning. In the antithymocyte serum-treated group, tumors were produced in cheek pouches and grew progressively in size until Day 21 with no sign of regression. Little host reaction was noticed histologically around the tumor grafts throughout the course. Distant metastases were revealed at autopsy in 9 of 12 animals from Day 14 of inoculation on, and all the experimental animals died by Day 23. Six of the 9 hamsters with metastases died of tumor. By means of the back-transplantation test, the metastatic tumor cells were shown to be consistent with Yoshida sarcoma cells. In hydrocortisone-treated and untreated groups, the tumor size reached a maximum on Day 21 and Day 5, respectively, and then regression followed. No metastasis was detected in either control group.