Yolk-sac carcinoma of extra-embryonic origin in the 129 Sv/Sl mouse.

Displacement of the visceral yolk-sac in fetectomized rats and hamsters does not only induce benign teratomas but may also lead to the development of malignant yolk-sac carcinoma. In the mouse, displacement of this extraembryonic membrane readily induces teratoma but until now yolk-sac carcinoma has never been observed in this species. In the present study we report the development of yolk-sac carcinoma in 129 Sv/Sl mice after a long latent period (8 months). The tumor is composed of visceral and parietal patterns in the primary neoplasm and in its metastases. It develops from the extra-embryonal part belonging to normal (+/+), heterozygous (Sl/+) or sterile (Sl/Sl) embryos, which proves that these yolk-sac carcinomas are not of germ-cell origin.