The Importance of Imprinting in the Human Placenta
Figure 1
Villous trophoblasts of the human placenta grow as a branched structure, maximising exchange with maternal blood. Extravillous trophoblast invade into the maternal endometrium, and some cells colonise maternal spiral arteries, expanding them to maximise blood flow. ♂ = Paternally expressed; ♀ = maternally expressed. Imprinted genes are important during fetal growth. Some, such as GNAS, UBE3A, and PLAGL, have physiological impact on the fetus only. Other genes may influence growth in utero via the placenta, or the fetus and placenta. The IUGR seen in SRS, and overgrowth in BWS are suggestive of a role of IGF2 in the human placenta.
