The definitive architecture of the mammalian body is established shortly after implantation of the embryo in the uterus. The antero-posterior, dorso-ventral and medio-lateral axes of the body become organized under the control of gene networks that coordinate the transcription of DNA in various regions of the embryo. Researchers from the University of Geneva (UNIGE), the University of Cambridge, UK, and the Federal Institute of Technology Lausanne (EPFL) now report the ability of mouse stem cells to produce pseudo-embryos that display similar capacities.