EXPRESSION OF MESSENGER-RNA FOR VASCULAR ENDOTHELIAL GROWTH-FACTOR INHUMAN PLACENTA

Implantation and growth of the placenta requires extensive angiogenesi s to establish the vascular structures involved in exchange. Failure t o establish adequate blood supply to the fetus may have serious clinic al consequences such as intrauterine growth retardation Vascular endot helial cell growth factor (VEGF) is a recently identified growth facto r with significant angiogenic properties. We have demonstrated the pre sence of four species of mRNA encoding VEGF in both first trimester an d term placenta. In situ hybridization was used to localize the sites of expression of VEGF mRNA in these tissues. VEGF expression was seen in villous trophoblast in the first trimester and in extravillous trop hoblast at term, and in both fetal macrophages within the villi and ma ternal macrophages in the decidua. Glandular epithelium in maternal de cidua also expressed VEGF mRNA. The strongest site of expression was i n maternal macrophages adjacent to Nitabuch's stria, a zone of necrosi s at the site of implantation. This complex pattern of expression sugg ests that VEGF is involved in angiogenesis on both maternal and fetal sides of the placenta and that macrophages are the primary source of V EGF. However, VEGF may also play a role in term placenta, when extensi ve angiogenesis has diminished, possibly regulating vascular permeabil ity.