In DepthEvolution

Tamed immune reaction aids pregnancy

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Science  19 Jan 2018:
Vol. 359, Issue 6373, pp. 260
DOI: 10.1126/science.359.6373.260

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The riskiest moment in any human pregnancy is arguably when the fertilized egg attaches to the womb wall and tries to establish a lifeline between embryo and mother. About half of in vitro pregnancies fail during this implantation stage, and many natural pregnancies end then as well. Now, researchers comparing pregnancy in opossums and several other mammals have shown how precise control of an immune process, inflammation, is critical to success or failure. In work reported at the annual meeting of the Society for Integrative and Comparative Biology in San Francisco, California, a Yale University team found that so-called placental mammals have tweaked an ancient inflammatory process to enable embryos to implant and persist in the womb. Placental mammals—named for the mass of tissue in the uterus that serves as the interface between mother and fetus—have specialized uterine cells that suppress the release of a key immune-stimulating molecule. This suppression may help delay the rejection of the embryo until it's fully developed, they reported.