Development of teratomas from the ectoderm of mouse egg cylinders.

We studied the developmental capacities of the primary ectoderm and endoderm of 6-day embryos of hybrids between strains 129/Sv-SIJ C P and A/He mice by grafting these germ layers into the testes of adult mice for 30 days. Grafts of embryonic ectoderm gave rise to teratocarcinomas composed of undifferentiated embryonal cells and derivatives of all three germ layers including respiratory and alimentary epithelium. Grafts of extraembryonic ectoderm gave rise to invasive trophoblastic giant cells. Grafts of endoderm did not develop