Structural changes in human placenta and its vascular bed in syndrome of placental failure

Study of born placentas with chronic functional failure established in the III pregnancy trimester has revealed several characteristic structural alterations of placental villi and of its vascular bed elements. There has been shown a decrease of the number of terminal villi and an increase of their sizes (approximately 3 times) as compared with norm, a change of transformation of cytotrophoblast into syncytiotrophoblast, thickening of vascular endothelium, a decrease of the number of capillaries-sinusoids, and a decrease of the number of syncytiocapillary membranes, which leads to deterioration of conditions of the maternal-fetal diffuse exchange. It has been established that in placental failure, expression of the vascular endothelial growth factor (VEGF) by cytotrophoblast cells, syncytiotrophoblast, and Kashchenko-Hoffbauer cells is enhanced as compared with norm, which can be considered an adaptive reaction to a decrease of intensity of placental blood circulation.