Abstract
Tissues from human embryos, 10-16 weeks old, were implanted and propagated in X-irradiated rats or non-irradiated hamsters, both treated with cortisone. Successful serial transplants were made. Since the individual generations could be maintained for as long as 50 days in treated hamsters, they were found to offer excellent material for research purposes. Lung, skin, cartilage, and trachea grew especially well.