How Does Male DNA Get Into a Woman’s Brain?
Some women always have men on the brain. And some women literally have men in their brains. A new study in PloS ONE found that quite a few female brains contain male DNA. This genetic material presumably passes into a mother while she is pregnant with a male fetus. Although we already knew that fetal cells can enter a mother’s body, until now, it was unknown whether the cells could pass into the brain as well, because the blood brain barrier normally blocks large molecules and foreign substances from entering the brain.
To explore the possibility of brain microchimerism—the presence of genetically distinct cells in a host’s body—researchers examined autopsy specimens from 59 deceased female subjects, who either had no neurological disease or had suffered from Alzheimer’s. The scientists found that 63% of the brains contained male cells distributed throughout the organ, and that this microchimerism did not fade away over time: the brain of one 94-year-old woman still contained male cells. These results suggest that during pregnancy, the blood brain barrier becomes more permeable and allows fetal cells to enter the mother’s brain.