With a scientific perspective, researchers from the University of Cambridge have concluded that the typical squabbles between men and women are far older than romantic relationships; they begin in the mother's womb during fetal development, as paternal and maternal genes clash. In a study recently published in the journal "Developmental Cell," researchers identified a key signal used by the fetus to control its nutrient supply from the placenta, revealing a tug-of-war between genes inherited from the father and the mother.
The researchers state that the study, conducted on mice, may help explain why some babies experience poor growth in the womb. They used genetically modified mice to demonstrate how the fetus emits a signal to encourage the growth of blood vessels within the placenta, which also causes modifications in other placenta cells to allow more nutrients to pass from the mother to the fetus.
As the fetus grows, it needs to meet its increasing food requirements from the mother, feeding through the blood vessels in the placenta, an organ that develops in the womb during pregnancy. The placenta supplies oxygen and nutrients to the fetus while removing waste from the child's blood and attaches to the uterine wall, from which the umbilical cord leading to the fetus emerges.
According to the study, the growth of 10 to 15 percent of children occurs poorly in the womb, often resulting in reduced blood vessel growth in the placenta.
To clarify the details of the genetic conflict, Dr. Ionel Sandovici, the lead author of the study, explains, “When the fetus grows in the womb, it needs to get the right amount of nutrients from its mother, and healthy blood vessels in the placenta are essential to help with that.” He elaborates, “We have identified one of the ways the fetus communicates with the placenta to stimulate the correct expansion of these blood vessels, and when that connection is broken, the blood vessels do not develop properly, and the baby will struggle to get all the food it needs.”
Interestingly, the study reveals that the fetus sends a signal known as IGF2 to the placenta via the umbilical cord, and the abundance of this gene is linked to enhanced growth. When IGF2 is insufficient, growth slows down, likely leading to poor growth at birth and potentially exposing children to mortality; such individuals may be more susceptible to diabetes and heart problems in adulthood.
The researchers indicate that the response to the IGF2 gene occurs in the blood vessels of the placenta through another protein called IGF2R, which is produced by two inherited genes from the father and the mother. Dr. Miguel Constandia, the principal author of the study, clarifies, “The genes expressed by the father are greedy and selfish. They want to obtain the most resources the mother has. Conversely, the genes expressed by the mother work to balance these demands.”
He continues, “In our study, the father’s gene increases the fetus's needs for more blood vessels and nutrients, while the mother’s gene in the placenta tries to control the amount of food it provides,” describing this process as “a tug-of-war, a battle of the sexes at the genomic level.”
Ultimately, the researchers state that their findings will lead to a better understanding during pregnancy of the communication process between the fetus, the placenta, and the mother, potentially leading to new ways to measure IGF2 levels in the fetus and develop methods to help use medications to balance these levels or promote normal blood vessel growth in the placenta.
