A murine ovarian tumor with unique metastasizing capacity

A transplanted murine ovarian tumor (M5076/73A, M5, of $\text{C57B1}\text{6}$ origin) with unique metastatic potential is described. After i.m. or s.c. inoculation of the M5 ovarian tumor, spontaneous metastases were consistently observed in liver, spleen, kidney, ovary and uterus, but lung lesions were not usually found. Even after i.v. inoculation the tumor showed a selective tropism for the abdominal organs mentioned. When M5 ovarian carcinoma cells were injected i.p., the tumor grew as scattered lesions in the abdomen and resulted in carcinomatous ascites. Surgical excision of i.m. tumors as early as 5days after implantation failed to protect mice against metastases, suggesting early widespread dissemination from the primary lesion. The tumor was poorly immunogenic as assessed by in vivo immunization with irradiated cells and by concomitant immunity experiments.