Experiments with the Embryo takes smaller steps towards the formation of a livestock of human organs

The perpetual shortage of human organs for transplant has researchers turning to farm animals. Several biotech companies are genetically engineering pigs to make their organs more compatible with the human body. But some scientists are pursuing a different solution: growing fully human organs in pigs, sheep, or other animals, which could then be harvested for transplants. The idea is biologically daunting and ethically fraught. But a few teams....