Vascular Remodeling at the Maternal-fetal Interface: Placental Interactions with Uterine Blood Vessels and the Lymphatic Circulation During Pregnancy PDF Download
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Author: Kristy Red-Horse
Publisher:
ISBN:
Category :
Languages : en
Pages : 298
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Book Description
The placenta induces important vascular changes in the uterus during pregnancy that allow the mother to adequately support growth and development of the embryo/fetus. Specifically, the uterine vasculature must incorporate the placenta into the maternal circulation facilitating mechanical attachment and nutrient/waste exchange. As they invade the uterine wall, placental cytotrophoblasts remodel resident blood vessels in a manner that channels maternal blood to and from the placenta. Although both sides of the circulation are involved in this process, remodeling is biased towards uterine spiral arterioles. An ultrastructural (scanning electron microscopy) study that was completed as a part of this thesis dramatically illustrates the unusual nature of this process.
Author: Kristy Red-Horse
Publisher:
ISBN:
Category :
Languages : en
Pages : 298
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Book Description
The placenta induces important vascular changes in the uterus during pregnancy that allow the mother to adequately support growth and development of the embryo/fetus. Specifically, the uterine vasculature must incorporate the placenta into the maternal circulation facilitating mechanical attachment and nutrient/waste exchange. As they invade the uterine wall, placental cytotrophoblasts remodel resident blood vessels in a manner that channels maternal blood to and from the placenta. Although both sides of the circulation are involved in this process, remodeling is biased towards uterine spiral arterioles. An ultrastructural (scanning electron microscopy) study that was completed as a part of this thesis dramatically illustrates the unusual nature of this process.
Author: Yuping Wang
Publisher: Biota Publishing
ISBN: 1615047514
Category : Medical
Languages : en
Pages : 126
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Book Description
The placenta is an organ that connects the developing fetus to the uterine wall, thereby allowing nutrient uptake, waste elimination, and gas exchange via the mother's blood supply. Proper vascular development in the placenta is fundamental to ensuring a healthy fetus and successful pregnancy. This book provides an up-to-date summary and synthesis of knowledge regarding placental vascular biology and discusses the relevance of this vascular bed to the functions of the human placenta.
Author: Yuping Wang (MD.)
Publisher: Morgan & Claypool Publishers
ISBN: 1615040455
Category : Health & Fitness
Languages : en
Pages : 99
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Book Description
The placenta is an organ that connects the developing fetus to the uterine wall, thereby allowing nutrient uptake, waste elimination, and gas exchange via the mother's blood supply. Proper vascular development in the placenta is fundamental to ensuring a healthy fetus and successful pregnancy. This book provides an up-to-date summary and synthesis of knowledge regarding placental vascular biology and discusses the relevance of this vascular bed to the functions of the human placenta.
Author: R.K. Miller
Publisher: Springer Science & Business Media
ISBN: 1461581095
Category : Medical
Languages : en
Pages : 365
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Book Description
The optimal function of the placenta and thus fetal well being largely depends upon the integrity of both the fetal and maternal circulations of the placenta. Intense basic research concerned with placental vascularization and blood flow has been performed for the past 30 years, beginning with the classical morphological descriptions of the placental vessels by Boe (1953) and Arts (1961), as well as with the radioangiographic studies of maternal placental circulation in the human by Borell (1958) and in the rhesus monkey by Ramsey (1962). The scientific framework presented by these investigators has been filled and completed by numerous investigators, leading to more morphological details, functional considerations, and pathological understanding. For an extended period of time, this research has been of primarily academic interest by increasing our insights into one important system of the placenta, yet having nearly no practical importance. Recently, this situation has changed dramatically: in vitro studies of the isolated, dually perfused human placenta and in vivo studies of placental circulation for diagnostic purposes have raised an enormous interest in basic research data. New methods like Doppler Ultrasound and NMR became available. These technics have enabled the obstetrician to study fetal and placental hemodynamics in vivo. Meanwhile, such methods are becoming incorporated into the daily obstetrical routine, to some degree without an adequate background knowledge of placental vascularization and blood flow, since such experience is currently available to only a small group of experts.
Author: Rojan Saghian
Publisher:
ISBN:
Category : Placenta
Languages : en
Pages : 228
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Book Description
The placenta is a fetal exchange organ that transfers nutrients and oxygen from mother to baby during pregnancy. Establishment of an adequate blood supply to the placenta is critical for pregnancy success. To do this, specialised placental cells, called trophoblasts, invade into the mother’s uterus and act to remodel the mother’s most distal uterine blood vessels, the spiral arteries (SAs). In the first trimester, the trophoblasts have been shown to at least partially occlude the SAs, restricting oxygenated blood flow to the placenta until approximately 10 weeks of gestation. In doing so, they create a physiologically normal low oxygen environment that is key for adequate placental developments but also significantly change the haemodynamic properties within the SA. Timing for SA unblocking by trophoblasts is important but it is not clear how it occurs. Trophoblasts also migrate along the SA length (against blood flow) and remodel them from tight muscular spirals into wide non vasoactive conduits that maximise volumetric blood flow for the remainder of pregnancy. Thus, beyond the first trimester, the volume of maternal blood delivered to the placenta is high, but its velocity is relatively low, avoiding damage to delicate placental tissue and maximising exchange between the maternal and fetal circulations. Disruptions to this remodelling process can lead to poor pregnancy outcomes, but the impact of SA remodelling on local blood flow rates, shear stress and subsequent SA remodelling is difficult to observe in vivo and largely unknown. To find out more about this delicate process of SA plugging by trophoblasts and its remodelling, more investigations in vivo and/or in vitro is required but doing that is also limited by obvious ethical constraints. Therefore, in silico approaches are more suitable to address these challenges. The aim of this thesis was to develop computational models of the utero-placental circulation throughout pregnancy and to link these models to trophoblast migration behaviours. First, we consider the first trimester of pregnancy, when the SA is plugged by trophoblasts. We present an analytically solvable model of the plugged SA and an alternative pathway for uterine blood flow, arteriovenous anastomoses. This model shows the existence of a physiological trophoblast plug prevents blood flow into the IVS, and decreases shear stress on the vessel wall upstream of the plug to a level that would generate permissible conditions for trophoblast migration and SA remodelling. The model provides estimates for the range of flow velocities through the SA in early pregnancy (which are not consistently observable by ultrasound) and the shear stress sensed by trophoblasts that are migrating in the SA. We then analyse the impact of fluid flow on trophoblast migration, by analysing an in vitro dataset of trophoblast migration in micro-fluidic channels in the context of the model of the plugged SA, with the aim of incorporating these data into an agent based model of trophoblast migration in the first trimester. This novel cell-based modelling framework was developed to simulate trophoblast migration within a SA under known environmental stimuli including blood flow and chemotaxis. Although chemotaxis sources and concentrations in the SA are still not well defined, we are able to parameterise the agent based model to data showing trophoblast responses to shear stress, and then to assess the impact of varying unknown parameters relating to chemotaxis in the model. The model suggests that chemotaxis and cell-cell interaction forces have a significant effect on the nature of trophoblast migration and plug dislodgment. We show that the plug could potentially dislodge due to cell migration from the plug to the vessel wall, or due to the formation of channels of high flow in the plug which occur due to asymmetries in the system or high flow velocity regions. Finally, we move beyond the first trimester and present a computational model of blood flow from remodelled SA openings into the intervillous space. This model shows that the structure of the placental tissue beyond the SA significantly impacts on ultrasound measured "jets" of flow. The model predicts that jets of flow observed by ultrasound are likely correlated with increased tissue porosity near the SA mouth and is proposed that observed mega-jets (flow penetrating more than half the placental thickness) are only possible when SAs open to regions of the placenta with very sparse tissue structures. Therefore, it is postulated that placental tissue density must decrease at the SA mouth through gestation, supporting the hypothesis that blood flow from SAs influences placental development. Computational models developed in this study provide a new approach to understanding the process of trophoblast migration behaviours, SA remodelling and implications of inadequate remodelling. The presented modelling framework in this thesis provides a platform which can be customised to incorporate more realistic structural and functional data on the utero-placental circulation as it becomes available.
Author: Arthur Tremain Hertig
Publisher:
ISBN:
Category : Medical
Languages : en
Pages : 384
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Book Description
Author: Olutoyin A. Olutoye
Publisher: Cambridge University Press
ISBN: 1009088904
Category : Medical
Languages : en
Pages : 227
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Book Description
A practical book on the unique fetal conditions amenable to surgical corrections and the anesthetic considerations for mother and child.
Author: Christoph Lees
Publisher: Cambridge University Press
ISBN: 1107157374
Category : Medical
Languages : en
Pages : 281
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Book Description
Discover new concepts in cardiovascular and hemodynamic functionality in feto-maternal medicine, from leading experts in the field.
Author: Win Min Tun
Publisher:
ISBN:
Category : Fetus
Languages : en
Pages : 223
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Book Description
The placenta is an essential organ for a successful pregnancy as it develops to establish effective fetal and maternal blood supplies and materno-fetal gas exchange, both of which are crucial for fetal growth. Abnormal development of the structural components of the placenta are known to be associated with pregnancy complications including fetal growth restriction (FGR) and pre-eclampsia. The overall aim of this thesis is to understand how the placental structural aberrations observed in FGR pregnancies impact placental haemodynamics and materno-fetal gas exchange. In order to accomplish this aim, both in silico and in vitro experimental models are employed to analyse the interactions between placental structure and function in normal and FGR pregnancies.The thesis commences with an in silico study which aims to predict how the structure of the placenta impacts on the mechanical shear stress sensed by endothelial cells that form the walls of placental capillaries. A computational model of feto-placental circulation,with structure parameterised with previously published morphometric data from normal and FGR pregnancies, was used to predict placental microvascular blood flow and shear stress in normal and FGR placentae. The model predicts an elevated microvascular shear stress in FGR placentae in comparison to normal placentae and that the main parameters influencing the elevated shear stress in FGR placentae are placental volume, vascular density, radius and length of individual vascular branches. Shear stress cannot be directly measured in vivo, however, the anatomical model of the placenta considered here provides the first predictions of the magnitude and distribution of shear stress in normal and FGR placentae. The next step is to determine whether this mechanical stress can impact on endothelial cell behaviours. Using an in vitro shear stress experiment, the predicted placental microvascular shear stresses were applied to vascular endothelial cells. These endothelial cells migrated more slowly and more persistently when they were exposed to the shear stresses of FGR conditions, suggesting that normal function of endothelial cells is impaired in FGR placentae, compromising the process of blood vessel formation. We, therefore, propose a vicious cycle in FGR pregnancy, where the elevated shear stress resulting from abnormal vascular structure undermines blood vessel formation, aggravating pre-existing vascular structure abnormalities. The morphology based feto-placental haemodynamic model is extended in two ways. First the model is extended to provide a complete model of the entire fetal circulation. This allows prediction of scenarios relevant to fetal survival in a multi-scale approach, including the interaction between fetal blood pressures, cardiac output and the shear stress in the placental capillaries. Using data from the literature we explore the impact of placental resistance due to structural abnormalities on fetal cardiac function. Then, we take steps toward a personalised approach to modelling the feto-placental circulation by analysing the chorionic vascular network in normal and FGR placentae. We confirm that this network contributes to overall placental resistance in individuals, and quantify how the characteristics of this network impact on placental function in FGR. Finally, in order to understand how the placental villous structure affects on placental exchange function, a 3D computational model of placenta representing the whole organ has been developed. Normal and FGR villous structure were parameterised as reported in previous morphometric studies. The reduced villous density in FGR placentae negatively impacts the maternal blood flow velocity into intervillous space (IVS), resulting in impaired materno-fetal gas exchange and fetal growth.This thesis demonstrates the influence of placental villous and vascular structure on placental vascular shear stress and materno-fetal oxygen exchange, and contributes to the understanding of the pathophysiology of fetal growth in FGR pregnancies. It provides a concept that the in vivo physiological data, that are difficult to assess, could be predicted by developing a replica of biological system computationally.
Author:
Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 884
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Book Description
