Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain
the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in
Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles
In the earliest stages of mammalian development, individual cells possess the unrestricted potential to form a new organism. Researchers are closing in on the goal of growing these cells in the laboratory.
The evanescent state of totipotency — the ability of a cell to form every other cell type required to generate a new organism — is difficult to study in developing embryos. Finding a way to propagate totipotent cells in culture would open up fresh avenues for research into early development. Cultured totipotent cells could also be powerful tools for deriving genetically modified animals for research or agricultural biotechnology, or for the conservation of endangered species, and could help to improve assisted-conception techniques in humans. A paper in Nature1, together with two other studies, in Cell Stem Cell2 and Nature3, describes substantial progress towards the goal of generating renewable cultures of totipotent stem cells in the laboratory.