The Placenta: A Maternofetal Interface

Abstract

The placenta is the gatekeeper between the mother and the fetus. Over the first trimester of pregnancy, the fetus is nourished by uterine gland secretions in a process known as histiotrophic nutrition. During the second trimester of pregnancy, placentation has evolved to the point at which nutrients are delivered to the placenta via maternal blood (hemotrophic nutrition). Over gestation, the placenta must adapt to these variable nutrient supplies, to alterations in maternal physiology and blood flow, and to dynamic changes in fetal growth rates. Numerous questions remain about the mechanisms used to transport nutrients to the fetus and the maternal and fetal determinants of this process. Growing data highlight the ability of the placenta to regulate this process. As new technologies and omics approaches are utilized to study this maternofetal interface, greater insight into this unique organ and its impact on fetal development and long-term health has been obtained.

Fetal Growth Associated with Maternal Rheumatoid Arthritis and Juvenile Idiopathic Arthritis

“…As majority of fetal weight gain occurs during the third trimester of pregnancy, both internal and external insults among patients with RA/JIA may result in placental insufficiency at the later stages of pregnancy, hence compromising fetal development during that period. 40,41…”

Reducing the Risk of Pre-Eclampsia in Women with Polycystic Ovary Syndrome Using a Combination of Pregnancy Screening, Lifestyle, and Medical Management Strategies

“…Normal development of the placenta involves a complex network of communication signals between fetal-derived trophoblasts and a broad range of maternally derived endometrial cells [ 25 ]. The fetal-derived precursor cells of the placenta are affected by sperm-derived signals to endometrial cells prior to fertilization [ 70 , 71 ], paternal and maternal genetics [ 72 ], imprinted genes [ 73 ], epigenetic reprogramming following fertilization [ 74 ], nutritional components of oviduct fluid from cells lining the fallopian tube prior to implantation [ 24 , 75 ], histotrophic nutrition during the first trimester [ 76 ], and hemotrophic nutrition following the establishment of significant blood flow into the placental intervillous space [ 77 ]. Disturbances of the normal physiology in any of these components could lead to abnormal trophoblast–decidual dialogue and contribute to deficient trophoblast invasion into the uterus and impaired spiral artery remodeling, resulting in placental hypoperfusion and syncytiotrophoblast stress, as is known to occur in PE ( Figure 1 ) [ 69 ].…”

“…During implantation and throughout the first trimester, both the placenta and embryo obtain nutrition from histotroph fluid that is derived from maternal endometrial gland secretions [ 24 ]. These secretions provide glucose, lipids, glycoproteins, and growth factors that stimulate the rapid proliferation of villous trophoblasts, extravillous trophoblast invasion, spiral artery remodeling, and normal development of the placenta [ 77 , 84 ]. At the start of the second trimester, blood enters the intervillous space, resulting in hemotrophic nutritional exchange between the maternal and fetal circulations [ 85 ].…”

“…Although insulin-sensitive glucose transporters are expressed in the placenta, the majority are not responsive to insulin stimulation [ 31 ]. Glucose transporters on the microvillous membrane of the syncytiotrophoblast move glucose into the cytoplasm via facilitated diffusion down the concentration gradient [ 77 ]. As a result, placental glucose transport to the fetus is mostly insulin-independent.…”

Collateral Damage in the Placenta during Viral Infection in Pregnancy: A Possible Mechanism for Vertical Transmission and an Adverse Pregnancy Outcome

“…The placenta is a hybrid organ comprising fetal and maternal tissues [ 1 ]. It has three main functions: (a) maintaining homeostasis between nutrients and waste in the fetus, (b) regulating the fetal environment and maternal immune response to avoid rejection, and (c) establishing a barrier against microorganisms [ 2 , 3 ]. To fulfill this purpose, cells constituting the placenta arrange themselves to create anatomical and functional units defined as chorionic villi.…”