Human–animal chimaeras are an exciting yet challenging area of research. Human cells are coaxed to grow in animal embryos, allowing researchers to study human tissue development. But the long-term ...

Low iron levels can flip the genetic switch on a mouse's sex during development, causing XY embryos to grow female features.

To determine baseline rates of meiotic aneuploidy and structural imbalances before mitotic cell division, the authors examined fertilized oocytes, which showed a low level of aneuploidy 7.