Pure Yolk Sac Carcinoma of the Mouse Uterus: Report of 8 Cases

: This report covered the pathologic features, behavior, metastases, and results of transplantation of pure yolk sac carcinomas that were primary in the uterine horn of 8 mice; 6 mice were strain C3H and 2 were strain HR, and they varied from 10 to 23 months of age. Three of the mice had never been treated. Of the 5 that had, the treatment was different for each mouse. Therefore, treatment could not be correlated with tumor development. At least 5 mice were nulliparous; in fact they had never been mated, so in these some mechanism involving parthenogenesis must have been operative to account for the tumor. The tumors were identified as being primary in the uterus and occupied and distended the cavity of one uterine horn where they were polypoid or plaquelike. The neoplastic yolk cells replaced the endometrial stroma forming a support for the original endometrial glands. In time the tumor cells destroyed many of the endometrial glands. That the glands present in the primary uterine horn tumors were the original glands of the endometrium and not neoplastic glands was attested by their absence from the secondary neoplastic deposits in 4 mice in which the tumor had spread to areas outside the cavity of the uterus and from the neoplastic tissue of the tumor transplants in the recipient mice.