You're familiar with the story: a sperm and an egg meet to create an embryo, which has the potential to give rise to new life. But what if you could create a sperm or egg from any cell, even a single skin cell? Biologist Katsuhiko Hayashi discusses the science of in vitro gametogenesis (IVG) — an experimental technique for creating lab-made sperm or eggs out of just about any type of cell — and explores its implications for endangered species, human reproduction and more.