[The human placenta and its pathologies: focus on oxygen].
At the time of placentation, the conceptus surrounds itself with a trophoblastic layer where the villous tree develops and the uteroplacental circulation takes place. Analysis of the modalities of maternal blood entrance demonstrated a physiological hypoxia ending with the first trimester of pregnancy. Moreover, cultures of first trimester villous explants have shown the role of oxygen in extravillous cytotrophoblast proliferation, decidual invasion and spiral artery remodeling. Oxygen appears to be a key factor controlling the mechanism of placentation by regulating the transcription of several genes, such as VEGF (vascular endothelial growth factor), leptin, etc. These genes are turned on or off as a function of oxygen partial pressure via an oxygen sensor. Oxygen is now considered to be implicated in the development of several pathologies of pregnancy. It is involved at different steps in the cascade of events leading to preeclampsia. Positive correlations have been observed between oxygen partial pressure and abnormal development of the villous tree in intrauterine growth retardation, and in maternal anemia or pregnancy in altitude.
Challier
Jean-Claude
JC
Physiopathologie de l'Implantation et du Développement, Upres 2396, Université Pierre et Marie Curie, Faculté de médecine Saint-Antoine, 27, rue de Chaligny, 75012 Paris, France et Hôpital Tenon, 4, rue de la Chine, 75020 Paris, France. jcch@ccr.jussieu.fr
Uzan
Serge
S
D000328:Adult; D002824:Chorionic Villi / Q000502:physiology; D010064:Embryo Implantation; D005260:Female; D005317:Fetal Growth Retardation / Q000503:physiopathology; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D008431:Maternal-Fetal Exchange; D010100:Oxygen / Q000378:metabolism*; D010920:Placenta / Q000473:pathology* / Q000502:physiology*; D011247:Pregnancy
D010100:Oxygen