The placenta is a vital connection that provides a foetus with nutrients from its mother’s blood. However, if the placenta forms incorrectly it can endanger the lives of both mother and foetus. Syncytial knots are pieces of shed tissue from the developing placenta – one is shown here (bright circle) in the lining of the uterus. If these reach the mother’s bloodstream they can cause sudden death. Nonetheless, the placenta doesn’t block all cells from the foetus from passing through to the mother. Foetal cells known as extravillous trophoblasts (EVTs) do cross over, and scientists have recently found that they enter the mother’s bloodstream earlier than previously thought. This crossing helps shape the border between the mother’s bloodstream and the placenta. The EVTs could also be helping the mother’s immune system get accustomed to the foetus’s cells, and prevent it attacking them.
Written by Esther Redhouse White
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