Japanese researchers are developing a "lab-on-a-chip" to improve the success rates of IVF techniques. Researchers think that manipulating eggs and sperm, and the unphysiological (abnormal) environment of the dish in which fertilisation and initial development occurs, may have an adverse effect on the success of IVF. To combat the problem, Teruo Fujii from the University of Tokyo has produced a microfluidic device which can take 20 eggs, mix them with sperm and then nurture them as they are fertilised and begin to develop. To create a more ideal environment the team grow a carpet of endometrial cells, which normally line the uterus, in their device. This means that growth factors and other signals from these cells can reach the developing embryo, more closely mimicking the enviroment in the body. Initial tests using animals have been encouraging. Out of fifty eggs fertilised on the chip, 30 sucessfully developed into early embryos compared with 26 out of fifty produced the traditional way. In a further study, when the embryos were placed in the uterus to test their long-term viability, 44% of those produced on the chip grew into mice compared with 40% of those produced using existing IVF approaches. Although the improvement appears quite modest, in a high stakes game like human infertility, 4% can make the difference between joy and heartbreak. The team have now permission to test their approach using human embryos, which they hope to start doing later this year.