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Placenta Sep 2017A significant proportion of children born preterm will experience some level of neurodevelopmental impairment. Changes in placental function have been observed with many... (Review)
Review
A significant proportion of children born preterm will experience some level of neurodevelopmental impairment. Changes in placental function have been observed with many antenatal conditions that are risk factors for preterm birth and/or poor neurodevelopment including fetal growth restriction and in-utero inflammation. This review will highlight placental factors that have been studied to understand the underlying mechanisms and identify biomarkers that lead to poor child neurodevelopmental outcomes. These include changes in gross morphological and histopathological structure and the placental inflammatory response to prenatal infection. Further, we will describe the placenta's role as both a barrier to maternally-derived bioactive substances critical for normal fetal brain development, such as cortisol, and a source of neuroactive steroids and neurotrophins known to have critical functions in neuronal proliferation, axonal growth, myelination and the regulation of apoptosis. Finally, emerging data supporting the potential utility of novel placental biomarkers in the early prediction of poor neurodevelopmental outcome in infants born both preterm and term will be discussed. These include the assessment of genetic variants (e.g. single nucleotide polymorphisms in placental tissue) and epigenetic biomarkers (e.g. placental microRNAs and placental DNA methylation). With the placenta the key tissue regulating the fetal environment, integration of observed changes in placental function with genetic and epigenetic variations may advance our ability to predict future infant health. Ultimately, this may facilitate targeted allocation of health resources with the aim of improving lifelong neurodevelopmental capability.
Topics: Biomarkers; Child Development; Female; Humans; Infant; Neurodevelopmental Disorders; Placenta; Pregnancy; Premature Birth
PubMed: 28864022
DOI: 10.1016/j.placenta.2017.06.009 -
Placenta Apr 2003The central role of the placenta in the pathogenesis of pre-eclampsia is undisputed. The evidence that maternal syndrome of pre-eclampsia is caused by a maternal... (Review)
Review
The central role of the placenta in the pathogenesis of pre-eclampsia is undisputed. The evidence that maternal syndrome of pre-eclampsia is caused by a maternal systemic inflammatory response (MSIR) is reviewed. The polymorphic nature of the inflammatory network explains the diversity of the varied signs of this condition. A key observation is that an MSIR is also a feature of normal third trimester pregnancy, but less severe than in pre-eclampsia. Hence pre-eclampsia is simply the extreme end of a continuum common to all pregnancies, with multiple contributing factors. Evidence is presented that apoptotic or necrotic debris shed from the syncytial surface of the placenta constitutes the inflammatory stimulus in all pregnancies. This model explains many features of pre-eclampsia including its occurrence with either larger placentae or small oxidatively stressed placentae. The clinical implications are that in terms of diagnosis or prediction there can never be a clear distinction between normal and abnormal. No test, predictive or diagnostic, can be expected to distinguish absolutely between different degrees of a problem that is common to all pregnancies. The possibility that the MSIR associated with third trimester pregnancy is nothing more than the maternal price for sustaining gestation is considered. Insulin resistance is a feature of normal pregnancy and also of systemic inflammatory states in non-pregnant individuals. It has been previously proposed that the insulin resistance of pregnancy is an important adaptation to divert maternal glucose to meet the needs of the foetus. Hence the MSIR, by causing maternal insulin resistance, may have substantial foetal advantages so long as it is not too severe.
Topics: Endothelium, Vascular; Female; Humans; Inflammation; Maternal-Fetal Exchange; Oxidative Stress; Placenta; Pre-Eclampsia; Pregnancy
PubMed: 12842410
DOI: 10.1053/plac.2002.0930 -
Journal of Ultrasound in Medicine :... Jan 1995We prospectively identified 12 patients who had a shelf at the margin of the placenta consistent with the diagnosis of circumvallate placenta. Ten patients were followed...
We prospectively identified 12 patients who had a shelf at the margin of the placenta consistent with the diagnosis of circumvallate placenta. Ten patients were followed to delivery and three placentas were sent for pathologic analysis. Circumvallate placenta was diagnosed by gross inspection in all three but was confirmed by microscopic analysis in only two. One of these patients had placental abruption and cesarean delivery for fetal distress at 27 weeks. Circumvallate placenta is another cause of uterine band, sheet, or shelf. The finding can be associated with a normal obstetric outcome but may predispose to placental complications.
Topics: Abruptio Placentae; Cesarean Section; Delivery, Obstetric; Female; Fetal Distress; Follow-Up Studies; Hematoma; Humans; Placenta; Placenta Diseases; Pregnancy; Pregnancy Outcome; Pregnancy Trimester, Second; Prospective Studies; Ultrasonography, Prenatal
PubMed: 7707472
DOI: 10.7863/jum.1995.14.1.21 -
Placenta Jan 2008Tissue samples are removed from placentas for a variety of reasons associated with a host of investigative techniques, including chorionic villus sampling, villus... (Review)
Review
Tissue samples are removed from placentas for a variety of reasons associated with a host of investigative techniques, including chorionic villus sampling, villus explant culture, cell culture, proteomic analysis, gene expression profiling, microscopy and morphometry. Apart from the latter, especially stereological analysis, many studies provide extremely limited information on how the samples were selected. At worst, we learn little more than the placenta was sampled. Sometimes, studies provide sufficient detail to reveal flaws in sampling, e.g. the selection of placentomes based on size rather than mere presence. Occasionally, the reader is informed, without further explanation, that representative samples were taken or that samples from placentas in different study groups were taken from standard or similar sites. Such statements raise doubts about the unbiasedness of the sampling process, leave the reader in ignorance of the quality of the final sample, thwart attempts at achieving study repeatability and compromise interpretations of the validity of study outcomes. And yet study outcomes depend critically on the selection process because sampling influences study errors, notably precision (random error) and bias (systematic error). This article aims to review the basic principles and virtues of random sampling in general and the practical utilities of variants of it. For many functional and structural studies, it suffices to randomise the positions of tissue samples but, in certain structural studies, orientation must also be randomised. Therefore, sampling tools for stereological estimation of membrane surface areas, tubule lengths and layer thicknesses are mentioned. Although emphasis is accorded to the placenta, the principles apply equally well to other organs and to lower levels of organisation including the subcellular. It is hoped that this review will inform future study designs, encourage greater transparency and facilitate sampling improvements.
Topics: Biopsy; Female; Humans; Placenta
PubMed: 17658596
DOI: 10.1016/j.placenta.2007.05.010 -
Journal of Comparative Physiology. B,... Mar 2006The aim of this review is to collate data relevant to understanding the evolution of viviparity in general, and complex placentae in particular. The wide range of... (Review)
Review
The aim of this review is to collate data relevant to understanding the evolution of viviparity in general, and complex placentae in particular. The wide range of reproductive modes exhibited by lizards provides a solid model system for investigating the evolution of viviparity. Within the lizards are oviparous species, viviparous species that have a very simple placenta and little nutrient uptake from the mother during pregnancy (lecithotrophic viviparity), through a range of species that have intermediate placental complexities and placental nutrient provision, to species that lay microlecithal eggs and most nutrients are provided across the placenta during development (obligate placentotrophy). In its commonest form, lecithotrophic viviparity, some uptake of water, inorganic ions and oxygen occurs from the mother to the embryo during pregnancy. In contrast, the evolution of complex placentae is rare, but has evolved at least five times. Where there is still predominantly a reliance on egg yolk, the omphaloplacenta seems to be paramount in the provision of nutrition to the embryo via histotrophy, whereas the chorioallantoic placenta is more likely involved in gas exchange. Reliance on provision of substantial organic nutrient is correlated with the regional specialisation of the chorioallantoic placenta to form a placentome for nutrient uptake, particularly lipids, and the further development of the gas exchange capabilities of the other parts of the chorioallantois.
Topics: Animals; Biological Evolution; Biological Transport; Extraembryonic Membranes; Lizards; Placenta; Viviparity, Nonmammalian
PubMed: 16333627
DOI: 10.1007/s00360-005-0048-5 -
Przeglad Lekarski 2015The proper placenta's structure and function are essential conditions to correct pregnancy's and labour's course. Nowadays the role of epigenetics in this organ is more... (Review)
Review
The proper placenta's structure and function are essential conditions to correct pregnancy's and labour's course. Nowadays the role of epigenetics in this organ is more carefully investigated. Some of epigenetics' modifications as DNA methylation, non-coding RNA action or histone modification are able to change the genes' expression without the change of DNA sequence. This phenomenon is particularly intensified in the placenta. Epigenetics placenta's irregularities can be responsible for many pregnancy pathologies, for example spontaneous miscarriage, pre-eclampsia or intrauterine growth retardation, and for many postnatal diseases, such as cancer or mental problems. In the future the monitoring of epigenetics placenta's modifications enables the estimation of pregnancy complications and postnatal diseases risk. Moreover, it will be possible to understand the role of epigenetics in functions the different kinds of cells, including cancer cells.
Topics: Epigenesis, Genetic; Female; Humans; Placenta; Pregnancy; Pregnancy Complications
PubMed: 27012129
DOI: No ID Found -
World Neurosurgery Nov 2023The development of microsurgical skills is crucial for neurosurgical education. The human placenta is a promising model for practicing vascular anastomosis due to its...
OBJECTIVE
The development of microsurgical skills is crucial for neurosurgical education. The human placenta is a promising model for practicing vascular anastomosis due to its similarities with brain vessels. We propose a 2-stage model for training in extracranial-to-intracranial anastomosis using the placenta.
METHODS
Initially, we propose practicing anastomosis in 2 adjacent placentas. Once successful, the procedure advances to a more challenging configuration that employs a 3-dimensionally printed skull with a window simulating a pterional craniotomy. It is positioned an intracranial placenta and an extracranial one, and the latter has a prominent vessel exposed toward the side of the craniotomy. Both placentas have one artery and vein cannulated in the umbilical cord, and we present an artificial placental circulation system for microvascular training that regulates pulsation and hydrodynamic pressure while keeping veins engorged with a pressurized bag. To verify anastomosis patency, we utilize sodium fluorescein and iodine contrast.
RESULTS
The 2-stage model simulated several aspects of microvascular anastomosis. Our perfusion system allowed for intraoperative adjustments of hydrodynamic pressure and pulsation. Using iodine contrast and fluorescein enabled proper evaluation of anastomosis patency and hydrodynamic features.
CONCLUSIONS
Training in the laboratory is essential for developing microsurgical skills. We have presented a model for microvascular anastomosis with artificial circulation and postoperative imaging evaluation, which is highly beneficial for enhancing the learning curve in microvascular procedures.
Topics: Humans; Female; Pregnancy; Neurosurgery; Placenta; Microsurgery; Anastomosis, Surgical; Iodine
PubMed: 37690578
DOI: 10.1016/j.wneu.2023.08.118 -
Advances in Experimental Medicine and... 2023The placenta is an intriguing organ that allows us to survive intrauterine life. This essential organ connects both mother and fetus and plays a crucial role in maternal... (Review)
Review
The placenta is an intriguing organ that allows us to survive intrauterine life. This essential organ connects both mother and fetus and plays a crucial role in maternal and fetal well-being. This chapter presents an overview of the morphological and functional aspects of human placental development. First, we describe early human placental development and the characterization of the cell types found in the human placenta. Second, the human placenta from the second trimester to the term of gestation is reviewed, focusing on the morphology and specific pathologies that affect the placenta. Finally, we focus on the placenta's primary functions, such as oxygen and nutrient transport, and their importance for placental development.
Topics: Pregnancy; Female; Humans; Placenta; Fetus; Placentation; Fetal Development
PubMed: 37466767
DOI: 10.1007/978-3-031-32554-0_1 -
Reproduction in Domestic Animals =... Jul 2019Macroscopic evaluation of the placenta is an essential post-partum examination in the alpaca and can be of special interest in case of abortion, premature birth or...
Macroscopic evaluation of the placenta is an essential post-partum examination in the alpaca and can be of special interest in case of abortion, premature birth or stillbirth. Since there are not many reference values regarding macroscopic properties of normal alpaca placentas, a small descriptive study was conducted. Only placentae from normally foaling alpaca mares, giving birth to healthy crias, after a full-term and uneventful gestation (±350 days; range 335-360 days) were taken into account (N = 11). Crias weighed (±SD) 7.7 ± 2.25 kg (range 5.5-10 kg), while the mean weight of the full-term placentas was 0.8 ± 0.19 kg, that is 10% of the bodyweight of the crias. The weight of the allantoamnion and chorion was 0.2 ± 0.07 kg and 0.5 ± 0.13 kg, respectively. The umbilical cord length was 8.8 ± 2.84 cm, and the length of the pregnant and non-pregnant uterine horns was 69.4 ± 12.77 cm and 54.5 ± 6.81 cm, respectively. The length of the corpus was 14.6 ± 4.68 cm, and the distance from the umbilicus to the corpus was 18.5 ± 6.13 cm. The tissue volume of the allantoamnion was 0.14 ± 0.079 L, and the chorionic volume was 0.37 ± 0.078 L. The surface area of the allantoamnion and the chorion was 87.6 ± 15.56 dm and 72.3 ± 9.28 dm , respectively. All placentas had small calcifications either around the umbilical cord alone or around the umbilicus and blood vessels of the pregnant uterine horn. These measurements could be used to macroscopically evaluate alpaca placentas, although more research is needed to extend our knowledge of macroscopic evaluation of normal and abnormal placentas.
Topics: Animals; Camelids, New World; Female; Placenta; Postpartum Period; Pregnancy; Umbilical Cord
PubMed: 31059204
DOI: 10.1111/rda.13453 -
Placenta Feb 2012The way in which maternal blood is associated with trophoblast prior to the formation of the different types of hemochorial placenta may be conveniently grouped into... (Comparative Study)
Comparative Study Review
The way in which maternal blood is associated with trophoblast prior to the formation of the different types of hemochorial placenta may be conveniently grouped into four main patterns: a transitory endotheliochorial condition; maternal blood released into a mass of trophoblast; maternal blood confined to lacunae; and fetal villi entering preexisting maternal blood sinuses. Although it might be considered logical that developing placentas would pass through an endotheliochorial stage to become hemochorial, this developmental pattern is seen only as a transient stage in several species of bats and sciuromorph rodents. More commonly a mass of trophoblast at the junction with the endometrium serves as a meshwork through which maternal blood passes, with subsequent organization of a labyrinth when the fetal vascular component is organized. The initial trophoblast meshwork may be cellular or syncytial, often leading to a similar relationship in the spongy zone and labyrinth. Old World monkeys, apes and humans have a lacunar stage prior to establishing a villous hemochorial condition. New World monkeys lack a true lacunar stage, retaining portions of maternal vessels for some time and initially forming a trabecular arrangement similar to though differently arrived at than that in the tarsier. In armadillos, preexisting maternal venous sinuses are converted into an intervillous blood space by intruding fetal villi. Variations from the major patterns of development also occur. The way in which the definitive placental form is achieved developmentally should be considered when using placental structure to extrapolate evolution of placentation.
Topics: Animals; Biological Evolution; Female; Humans; Placenta; Placental Circulation; Placentation; Pregnancy; Trophoblasts
PubMed: 22061678
DOI: 10.1016/j.placenta.2011.10.009