Researchers reveal how embryos implant in humans
30 September 2008
Work part-funded by the Wellcome Trust has revealed, for the first time, the process that governs embryo implantation in the uterus (womb) in humans. This research should increase understanding of why some embryos fail to implant, which is a leading cause of infertility.
Researchers have shown that the embryo and uterine lining 'talk' to each other, on the molecular level, when the embryo lands on the surface of the uterus wall. After this, cells from the embryo begin to invade the uterine lining, eventually connecting with the mother's blood vessels to form the placenta.
"We have shown that two proteins, called Rac1 and RhoA, control the invasion," says Professor Helen J Mardon from the Nuffield Department of Obstetrics and Gynaecology, John Radcliffe Hospital, Oxford and the University of Oxford, who led the study.
"The first stimulates cells in the uterine lining to move and allow the embryo to invade and implant properly while the second inhibits this. We believe this controlled balance of the two proteins is critical for successful implantation of the embryo," says Professor Mardon. They found that if the balance of the two proteins is altered, the cells of the uterine lining don't migrate and the embryo doesn't implant.
Professor Mardon worked with colleagues from Oxford and Professor Anne J Ridley from King's College, London. The researchers designed an experiment that mimics the stage in which an early-stage human embryo invades the lining of the uterus, in order to dissect the molecular processes behind this process.
Image: Six-day-old human embryo beginning to implant into the lining of the uterus; Yorgos Nikas, Wellcome Images
References
Grewal S et al. Implantation of the human embryo requires Rac1-dependent endometrial stromal cell migration. Published online in PNAS Early Edition, doi: 10.1073/pnas.0806219105.