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How does a mother manage to understand why her child is crying – because he is hungry, or because something hurts him? This maternal ability continues to amaze each new generation. Genetics may have found an explanation for it.
The invisible connection between mother and child is often not interrupted even when the child has grown up a long time ago. Many cases have been described when mothers, being many hundreds of kilometers from their adult children, felt that they were sick or in trouble. Psychologists talk about empathy and fusion. Mystics raise their eyes to the sky. But it seems that geneticists also have their own opinion on this matter.
A few decades ago, biologists were astonished to discover fragments of male DNA in the blood of several women who had recently given birth. Studies have established that we are talking about fetal embryonic cells that entered the mother’s body through the placenta during pregnancy. As it turned out, this phenomenon has existed for millions of years and is inherent in all placental mammals. It has been given the slightly intimidating name of microchimerism.
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Microchimerism is the migration of cells from one multicellular organism to another, related multicellular organism, bypassing sexual reproduction. Possible: migration of mother’s cells into the body of the fetus, cell exchange between twins in the womb, migration of cells from a previous pregnancy into the body of a younger child, microchimerism as a result of transfusion. If fetal cells cross the placental barrier and remain in the mother’s body, we are talking about embryonic (or fetal) microchimerism.
For a long time, the technical arsenal of scientists was not enough to study the phenomenon of microchimerism in detail. And even now there is no need to talk about its complete clarity. Although there is no shortage of hypotheses. According to one of them, fetal cells stimulate the mother’s immune system, helping to more effectively eliminate any possible health threats. Another theory, on the contrary, suggests that the fetal cells that are retained in the body of a woman (and they can remain there for decades) eventually begin to be rejected by the immune system, which causes severe autoimmune diseases.
Today it is known that most of the embryonic cells that have entered the mother’s body through the placenta are removed by the immune system shortly after childbirth. The rest have the characteristics of stem cells – they are embedded in organs and tissues, assimilating the “habits of neighbors.” So, a group of Chinese biologists conducted experiments on mice: embryonic cells were exposed to lactation hormones – and formed a tissue similar to that of the mammary glands.1.
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These data prompted the American geneticist Amy Boddy (Amy Boddy) and her colleagues to the idea of looking at microchimerism from the point of view of evolutionary necessity.2. They suggest that many of the maternal functions of the female body were formed precisely under the influence of the embryonic cells of the fetus, which at the physiological level “tune” the woman to provide for all the needs of the child. Scientists predict that the maximum number of embryonic cells can be found in those organs of mothers that are of paramount importance for the birth and life of the newborn. These are the pancreas, which is responsible for metabolism and maintaining the temperature balance of the fetus during pregnancy, the mammary glands, which provide nutrition to the born child, and the brain. The neural connections in it form the maternal attachment to the child. And it is possible that it is the presence in the mother’s brain of the embryonic cells of an already born child that allows her to perceive the needs of the baby as her own.
1 S. Wang et al. “Plasticity of the response of fetal mouse fibroblast to lactation hormones”. Online publication on the website of the journal Cell Biology International, January 2, 2013.
2 AM Boddy et al. «Fetal microchimerism and maternal health: A review and evolutionary analysis of cooperation and conflict beyond the womb». Online publication on the website of the magazine BioEssays from August 28, 2015.