- REVIEW PAPER - Fetal cells in maternal circulation - potentials for prenatal control ANGELOS DANIILIDIS1* and KOKKONA KOUZI-KOLIAKOU2 1 3rd Department of Obstetrics and Gynaecology, Hippokration Hospital, Thessaloniki 54124, Greece 2 Laboratory of Histology-Embryology, Medical School, Aristotle University, Thessaloniki 54124, Greece Abstract Multiple studies have already showed that intact fetal cells and fetal nucleic acids circulate freely in maternal blood, in contrast to the traditional knowledge that placenta is an impermeable barrier, which prevents any communication between maternal and fetal blood. Fetal cells in maternal blood are very rare and a major issue is to determine the real number of fetal cells present in maternal circulation. Numerous reports do not agree about the numbers of fetal cells and DNA, not only in various gestational ages but also in different pregnancies. Until now, five types of fetal cells have been isolated and detected from maternal blood: trophoblasts, lymphocytes, granulocytes, nucleated erythrocytes and progenitor cells. These cell types could potentially be used for prenatal diagnosis. However, there are some difficulties concerning the use of these cells for accurate prenatal control.   < back .