Deep placentation

Abstract

Deep placentation in human pregnancy is realised by deep invasion of the placental bed by the extravillous trophoblast, involving the decidua and the inner (junctional zone) myometrium. Interstitial invasion of the stroma and endovascular trophoblast invasion of the spiral arteries both occur. Deep endovascular trophoblast invasion into the myometrial segments of spiral arteries is important for proper placental functioning. Before this extended vascular invasion begins, decidua-associated vascular remodelling, which includes swelling and disorganisation of the vascular smooth muscle, occurs during a period of rising placental oxygen. This early remodelling step may accommodate the progressively increasing maternal blood flow to the developing placenta. The subsequent trophoblast-associated remodelling step enhances and stabilises the widening of the vessels, whereas the vascular smooth muscle and elastic lamina are replaced by a fibrinoid matrix with embedded trophoblast. Defective deep remodelling contributes to placental malfunctioning in complications of pregnancy.

Metabolic Pathways Involved in 2-Methoxyestradiol Synthesis and Their Role in Preeclampsia

“…At around 10 to 12 weeks of gestation, the trophoblast plugs begin to dissolve and endovascular trophoblast cells replace the maternal endothelial lining as far as the inner third of the myometrium, degrading the muscular and elastic component of the vessel walls. This results in the formation of low-resistance vessels required for the establishment of the definitive uteroplacental circulation and for adequate fetal growth 9,11 (Figure 1). At this time, maternal blood begins to flow into the intervillous space, where it takes over the responsibility of nourishing the developing embryo.…”

“…9 From the tips of these anchoring villous structures, EVCT cells derived from this proliferating cytotrophoblast invade the maternal decidua and differentiate further into interstitial and endovascular trophoblast cells. The invasion process begins at the center of the placental bed and expands progressively outward toward the lateral areas in the shape of a ring.…”

Inhibition of Lectin-Like Oxidized Low-Density Lipoprotein Receptor 1 Protects against Plasma/Hypoxia-Mediated Trophoblast Dysfunction Associated with Preeclampsia

“…Trophoblast replaces the arterial media and transforms the uteroplacental circulation into a high-flow, low-resistance system [36]. PE is thought to be associated with reduced placental perfusion and related hypoxia [37].…”

Assessment of Maternal Vascular Remodeling During Pregnancy in the Mouse Uterus

“…Mice that lack either NK cells or components of the IFN-γ signaling pathway fail to undergo these changes and this is associated with reduced fetal growth 6,7 , stressing the importance of an adequate blood supply to the fetoplacental unit. During early human pregnancy, the interstitial and endovascular invasion of extravillous trophoblast and their interaction with uNK cells are important for inducing vascular changes and promoting fetal growth [8][9][10] . uNK cells can orchestrate human trophoblast invasion through chemokines 11 and cytokines such as granulocyte macrophage -colony stimulating factor (GM-CSF) 12 .…”

“…uNK cells can orchestrate human trophoblast invasion through chemokines 11 and cytokines such as granulocyte macrophage -colony stimulating factor (GM-CSF) 12 . Shallow trophoblast invasion is associated with reduced arterial remodeling and pregnancy complications such as pre-eclampsia 9 …”