Culturing human embryos beyond blastulation: Pushing the limits and exploring the unexplored

Two articles recently published in Nature and Nature Cell Biology reported that early human embryos were successfully cultured beyond blastulation. This development heralds an important step toward exploring the unknown molecular events driving human pre-gastrulation development, but it inevitably raises the ante in the decades-old ethical debate on how to define early human life and how to save human lives through research without destroying another life in the process.