Teratocarcinomas rarely develop from embryos transplanted into athymic mice

Abstract

SEVEN-DAY-OLD mouse embryos transplanted to extra-uterine sites give rise to tumours that have been classified as either benign teratomas or malignant teratocarcinomas¹. The ratio of teratomas to teratocarcinomas varies from one mouse strain to another, suggesting the existence of teratocarcinoma-permissive and nonpermissive strains². Control of teratocarcinogenesis in this tumour system resides in the adult recipient of the embryonic graft and might involve the immune response. We report here that we have tested the hypothesis that the absence of cell-mediated immunity enhances the growth of transplanted embryos and facilitates the development of teratocarcinoma. Contrary to our expectations, our data indicate that embryos grafted into recipients with partial or total deficiency of cell-mediated immunity grow poorly and develop almost exclusively into benign teratomas.