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Biologists describe how embryo attaches to womb

September 29, 2008 |  2:40 pm

Embryo1Advances in treating infertility over the last three decades have also yielded a wealth of fascinating scientific information about the basics of human biology. Today, another mystery was explained by Oxford University scientists who showed just how a fertilized egg attaches to the womb and implants itself, thus beginning the pregnancy.

When an embryo comes in contact with the lining of the womb, chemical signals are exchanged that allows the cells of the embryo to invade the womb and, eventually, connect with the mother's blood supply to form the placenta. In lab experiments, the Oxford scientists discovered that two specific proteins are involved in this process.

"We have shown that two proteins, called Rac1 and RhoA, control the invasion," said Helen J. Mardon of Oxford University. "The first stimulates cells in the womb 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."

If the balance between these two proteins is altered, the cells of the womb lining won't move aside to allow for implantation, the researchers said. The failure of implantation is a major cause of infertility. Understanding the process could lead to the development of medications that help embryos implant properly. The study is published today in Proceedings of the National Academy of Sciences.

-- Shari Roan

Photo: An eight-cell embryo. Credit: AP Photo