Determining which products of advanced biotechnology are deserving of legal protections is essential to our own social architecture.

While the hope is to one day grow organs for transplantation into people, several technical and ethical challenges remain.

Researchers produce functional organs composed of both mouse and rat cells.

Andrzej Tarkowski’s research laid the groundwork for future advances in cloning, stem cell research, and in vitro fertilization.

The public gets to weigh in before the US government lifts its ban on such research.

Can mice with humanlike tissues better model drug effects in people?

Ethical issues attend the creation of animal-human chimeras.

Artist Brian Andrews uses human and veterinary x-rays to create haunting animated hybrids.

Researchers have bred monkeys derived from six different monkey parents.

Careful oversight is required to ensure that chimeras and transgenic animals continue to serve as powerful biomedical research tools.