The experimental research combined two types of stem cells and created a viable embryo – which the team say would provide an unlimited stock for medical research. The created embryos would also be used for medical treatment testing and help shed light on one of the biggest infertility enigmas - why embryos fail to implant in the womb. However critics say it is a huge step towards human cloning. The researchers believe the wonder creation could see mice being cloned in three years time, and humans two decades later.