The placental barrier is not the impenetrable wall that it was once presumed to be. During pregnancy, fetal cells pass into the mother, where they persist for decades after the pregnancy, leading to fetal microchimerism (FMc). Maternal cells also pass into the fetus, where they can persist long after birth of the child into adulthood, leading to maternal microchimerism(MMc). FMc and MMc represe...

The presence of fetal cells has been associated with both positive and negative effects on maternal health. These paradoxical effects may be due to the fact that maternal and offspring fitness interests are aligned in certain domains and conflicting in others, which may have led to the evolution of fetal microchimeric phenotypes that can manipulate maternal tissues. We use cooperation and confl...

icrochimerism is considered as the occurrence of small populations of cells with a diverse genetic setting within a person (1). Tissue microchimerism is enhanced during pregnancy and is frequently associated with femaledominant autoimmune disorders, response to injury from malignancy, and transplantation effect (2). Recently, a group of pathologists at Leiden University Medical Center in the Ne...