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Mekler T, Plitman Mayo R, Weissmann J, Marom G. Impact of tissue porosity and asymmetry on the oxygen uptake of the human placenta: A numerical study. Placenta 2022; 129:15-22. [PMID: 36183458 DOI: 10.1016/j.placenta.2022.09.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 08/17/2022] [Accepted: 09/14/2022] [Indexed: 12/14/2022]
Abstract
INTRODUCTION This study proposes a computational fluid dynamics model of a human placenta's independent exchange unit (placentome) to assess the effect that the inner villi distribution and decidual veins (DVs) location and number, have on the oxygen uptake. METHODS The internal placentome porosity distribution was altered in symmetric morphology, while asymmetry was introduced by varying the location and number of DVs. The DV asymmetry was introduced by either displacing them circumferentially, thereby changing the angle between them, or by adding DVs in the inlet cross-section. The results were analyzed by the changes in the normalized oxygen mass fraction and the oxygen uptake. RESULTS Oxygenated blood was shown to be delivered deeper into the placentome when the area of non-homogeneous porosity was larger. The largest oxygen uptake was achieved in the asymmetric model with the smallest angle distance between the DVs, where a 10% decrease relative to the farthest case was obtained. Placing DVs adjacent to the spiral artery opening enhanced the drainage of oxygenated blood. DISCUSSION This study demonstrates the importance of the local porosity distribution for the proper perfusion of the intervillous space and proposes a novel approach to improve our understanding of the role of the DVs in placental oxygen uptake.
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Affiliation(s)
- Tirosh Mekler
- School of Mechanical Engineering, Tel Aviv University, Tel Aviv, 6997801, Israel.
| | - Romina Plitman Mayo
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel.
| | - Jonathan Weissmann
- Department of Biomedical Engineering, The Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv, 6997801, Israel.
| | - Gil Marom
- School of Mechanical Engineering, Tel Aviv University, Tel Aviv, 6997801, Israel.
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Plitman Mayo R, Abbas Y, Charnock-Jones DS, Burton GJ, Marom G. Three-dimensional morphological analysis of placental terminal villi. Interface Focus 2019; 9:20190037. [PMID: 31485319 DOI: 10.1098/rsfs.2019.0037] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/15/2019] [Indexed: 11/12/2022] Open
Abstract
Transport of nutrients and waste between the maternal and fetal circulations during pregnancy takes place at the final branches of the placental villous trees. Therefore, and unsurprisingly, pregnancy complications have been related to the maldevelopment of terminal villi. However, a deep analysis of placental villous morphology has been limited by tissue processing and imaging techniques. In this proof-of-principle study, placental lobules were fixed by perfusion and small clumps of villi were stained, sectioned optically and reconstructed. Morphological and network analyses were suggested and demonstrated on samples of normal placentas. The results show that most parameters are almost constant within a placenta but that there exists an inter-individual variation. Network analysis suggests that the feto-placental capillary network has several paths within an individual villus, serving as an efficient transport system. Three-dimensional reconstruction from confocal laser scanning microscopy images is a potent technique able to quantify placental architecture and capture the significant irregularities in vessel diameter and membrane thickness. This approach has the potential to become a powerful tool to further our understanding of the differences in placental structure which may underlie pregnancy complications.
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Affiliation(s)
| | - Yassen Abbas
- Centre for Trophoblast Research (CTR), Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, UK.,Department of Pathology, University of Cambridge, Cambridge CB2 1QP, UK
| | - D Stephen Charnock-Jones
- Centre for Trophoblast Research (CTR), Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, UK.,Department of Obstetrics and Gynaecology, University of Cambridge, Cambridge CB2 0SW, UK
| | - Graham J Burton
- Centre for Trophoblast Research (CTR), Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, UK
| | - Gil Marom
- School of Mechanical Engineering, Tel Aviv University, Tel Aviv, Israel
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Advances in Human Placental Biomechanics. Comput Struct Biotechnol J 2018; 16:298-306. [PMID: 30181841 PMCID: PMC6120428 DOI: 10.1016/j.csbj.2018.08.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 08/06/2018] [Accepted: 08/12/2018] [Indexed: 11/21/2022] Open
Abstract
Pregnancy complications are a major clinical concern due to the related maternal and fetal morbidity. Many are caused through defective placentation, but research into placental function is difficult, principally because of the ethical limitations associated with the in-vivo organ and the difficulty of extrapolating animal models. Perfused by two separate circulations, the maternal and fetal bloodstreams, the placenta has a unique structure and performs multiple complex functions. Three-dimensional imaging and computational modelling are becoming popular tools to investigate the morphology and physiology of this organ. These techniques bear the potential for better understanding the aetiology and development of placental pathologies, however, their full potential is yet to be exploited. This review aims to summarize the recent insights into placental structure and function by employing these novel techniques.
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Luckhardt M, Leiser R, Kingdom J, Malek A, Sager R, Kaisig C, Schneider H. Effect of Physiologic Perfusion-Fixation on the Morphometrically Evaluated Dimensions of the Term Placental Cotyledon. ACTA ACUST UNITED AC 2016. [DOI: 10.1177/107155769600300402] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
| | - Rudolf Leiser
- Department of Obstetrics and Gynaecology, University of Berne, Berne, Switzerland: the Department of Veterinary Anatomy, Justus Liebig University, Giessen, Germany: and the Department of Obstetrics and Gynaecology, University College London Medical School, London, United Kingdom
| | - John Kingdom
- Department of Obstetrics and Gynaecology, University of Berne, Berne, Switzerland: the Department of Veterinary Anatomy, Justus Liebig University, Giessen, Germany: and the Department of Obstetrics and Gynaecology, University College London Medical School, London, United Kingdom; Department of Obstetrics and Gynaecology, UCL Medical School, 86-96 Chenies Mews, London WC1E 6HX, United Kingdom
| | | | | | - Christoph Kaisig
- Department of Obstetrics and Gynaecology, University of Berne, Berne, Switzerland: the Department of Veterinary Anatomy, Justus Liebig University, Giessen, Germany: and the Department of Obstetrics and Gynaecology, University College London Medical School, London, United Kingdom
| | - Henning Schneider
- Department of Obstetrics and Gynaecology, University of Berne, Berne, Switzerland: the Department of Veterinary Anatomy, Justus Liebig University, Giessen, Germany: and the Department of Obstetrics and Gynaecology, University College London Medical School, London, United Kingdom; Department of Obstetrics and Gynaecology, Schanzeneckstrasse 1, CH-3012 Berne, Switzerland
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Plitman Mayo R, Charnock-Jones DS, Burton GJ, Oyen ML. Three-dimensional modeling of human placental terminal villi. Placenta 2016; 43:54-60. [PMID: 27324100 DOI: 10.1016/j.placenta.2016.05.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 04/28/2016] [Accepted: 05/04/2016] [Indexed: 11/26/2022]
Abstract
INTRODUCTION Placental transport is the main factor affecting the health and development of the fetus. Due to the placenta's geometrical and mathematical complexity, the structure-function relations of placental terminal villi have not been successfully modeled. Hence, a novel modeling approach is proposed. METHODS Computational models of four different specimens were generated from the three-dimensional reconstruction of confocal laser scanning microscopic image stacks. To evaluate the capabilities of the proposed methodology, stationary oxygen diffusion transport was calculated in the terminal villus volumes. RESULTS The reconstructions automatically provided the spatial arrangement of the fetal capillaries inside the terminal villi. The surface and volume ratios between the fetal capillaries and the villus were also calculated, and the effects of model parameters on the placental diffusive capacity were assessed by parametric analysis. DISCUSSION The potential of three-dimensional reconstructions combined with finite element analysis as a research tool for the human placenta was tested. The methodology herein could serve in the future as a simulation platform for complicated in vivo and in vitro scenarios.
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Affiliation(s)
- Romina Plitman Mayo
- Centre for Trophoblast Research (CTR), Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK; Nanoscience Centre, Department of Engineering, University of Cambridge, Cambridge, UK
| | - D Stephen Charnock-Jones
- Centre for Trophoblast Research (CTR), Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK; Department of Obstetrics & Gynaecology, University of Cambridge, Cambridge, UK
| | - Graham J Burton
- Centre for Trophoblast Research (CTR), Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
| | - Michelle L Oyen
- Centre for Trophoblast Research (CTR), Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK; Nanoscience Centre, Department of Engineering, University of Cambridge, Cambridge, UK.
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Morales-Navarrete H, Segovia-Miranda F, Klukowski P, Meyer K, Nonaka H, Marsico G, Chernykh M, Kalaidzidis A, Zerial M, Kalaidzidis Y. A versatile pipeline for the multi-scale digital reconstruction and quantitative analysis of 3D tissue architecture. eLife 2015; 4. [PMID: 26673893 PMCID: PMC4764584 DOI: 10.7554/elife.11214] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 12/08/2015] [Indexed: 12/11/2022] Open
Abstract
A prerequisite for the systems biology analysis of tissues is an accurate digital three-dimensional reconstruction of tissue structure based on images of markers covering multiple scales. Here, we designed a flexible pipeline for the multi-scale reconstruction and quantitative morphological analysis of tissue architecture from microscopy images. Our pipeline includes newly developed algorithms that address specific challenges of thick dense tissue reconstruction. Our implementation allows for a flexible workflow, scalable to high-throughput analysis and applicable to various mammalian tissues. We applied it to the analysis of liver tissue and extracted quantitative parameters of sinusoids, bile canaliculi and cell shapes, recognizing different liver cell types with high accuracy. Using our platform, we uncovered an unexpected zonation pattern of hepatocytes with different size, nuclei and DNA content, thus revealing new features of liver tissue organization. The pipeline also proved effective to analyse lung and kidney tissue, demonstrating its generality and robustness.
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Affiliation(s)
| | | | - Piotr Klukowski
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Kirstin Meyer
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Hidenori Nonaka
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany.,Rohto Pharmaceutical, Tokyo, Japan
| | - Giovanni Marsico
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Mikhail Chernykh
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | | | - Marino Zerial
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Yannis Kalaidzidis
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany.,Faculty of Bioengineering and Bioinformatics, Moscow State University, Moscow, Russia
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Serov AS, Salafia C, Grebenkov DS, Filoche M. The role of morphology in mathematical models of placental gas exchange. J Appl Physiol (1985) 2015; 120:17-28. [PMID: 26494446 DOI: 10.1152/japplphysiol.00543.2015] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 10/08/2015] [Indexed: 02/07/2023] Open
Abstract
The performance of the placenta as a gas exchanger has a direct impact on the future health of the newborn. To provide accurate estimates of respiratory gas exchange rates, placenta models need to account for both the physiology of exchange and the organ morphology. While the former has been extensively studied, accounting for the latter is still a challenge. The geometrical complexity of placental structure requires use of carefully crafted approximations. We present here the state of the art of respiratory gas exchange placenta modeling and demonstrate the influence of the morphology description on model predictions. Advantages and shortcomings of various classes of models are discussed, and experimental techniques that may be used for model validation are summarized. Several directions for future development are suggested.
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Affiliation(s)
- A S Serov
- Physique de la Matière Condensée, Centre National de la Recherche Scientifique, Ecole Polytechnique, Palaiseau, France; and
| | - C Salafia
- Placental Analytics, LLC, Larchmont, New York
| | - D S Grebenkov
- Physique de la Matière Condensée, Centre National de la Recherche Scientifique, Ecole Polytechnique, Palaiseau, France; and
| | - M Filoche
- Physique de la Matière Condensée, Centre National de la Recherche Scientifique, Ecole Polytechnique, Palaiseau, France; and
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Abstract
Biobanks provide an important repository of samples for research purposes. However, for those samples to reflect the in vivo state, and for experimental reliability and reproducibility, careful attention to collection, processing and storage is essential. This is particularly true for the placenta, which is potentially subjected to stressful conditions during delivery, and sample collection may be delayed owing to routine postpartum inspection by clinical staff. In addition, standardisation of the collection procedure enables samples to be shared among research groups, allowing larger datasets to be established. Here, we provide an evidence-based and experts' review of the factors surrounding collection that may influence data obtained from the human placenta. We outline particular requirements for specific techniques, and propose a protocol for optimal sample collection. We recognise that the relevance of these factors, and of the sample types collected to a particular study will depend on the research questions being addressed. We therefore anticipate that researchers will select from the protocol to meet their needs and resources available. Wherever possible, we encourage researchers to extend their collection to include additional samples that can be shared on an international collaborative basis, with appropriate informed consent, to raise the quality, as well as quantity, of placental research.
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Kasukurthi R, Brenner MJ, Moore AM, Moradzadeh A, Ray WZ, Santosa KB, Mackinnon SE, Hunter DA. Transcardial perfusion versus immersion fixation for assessment of peripheral nerve regeneration. J Neurosci Methods 2009; 184:303-9. [DOI: 10.1016/j.jneumeth.2009.08.019] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2009] [Revised: 08/22/2009] [Accepted: 08/24/2009] [Indexed: 10/20/2022]
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Jirkovská M, Janáček J, Kaláb J, Kubínová L. Three-dimensional Arrangement of the Capillary Bed and Its Relationship to Microrheology in the Terminal Villi of Normal Term Placenta. Placenta 2008; 29:892-7. [DOI: 10.1016/j.placenta.2008.07.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2008] [Revised: 06/24/2008] [Accepted: 07/04/2008] [Indexed: 11/29/2022]
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Raijmakers MTM, Burton GJ, Jauniaux E, Seed PT, Peters WHM, Steegers EAP, Poston L. Placental NAD(P)H oxidase mediated superoxide generation in early pregnancy. Placenta 2006; 27:158-63. [PMID: 16338460 DOI: 10.1016/j.placenta.2005.02.013] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2004] [Revised: 02/11/2005] [Accepted: 02/14/2005] [Indexed: 11/20/2022]
Abstract
Early placental development is characterised by rapid cell differentiation and migration, matrix remodelling and angiogenesis. The enzyme NAD(P)H oxidase is a major source of superoxide anions implicated in signalling pathways regulating these processes in other systems. It is also thought to be involved in oxygen sensing and regulation of the expression of antioxidant genes. We therefore investigated NAD(P)H oxidase activity in placental tissues in early pregnancy and at term, and correlated this with antioxidant capacity. We collected placental tissues from women undergoing termination of pregnancy (n=19; gestational age 11(+6)+/-1(+0) weeks), and those with elective caesarean section at term after uncomplicated pregnancy (n=15; gestational age 38(+6)+/-0(+4) weeks). Tissues were assayed for superoxide production, using lucigenin chemiluminescence, and three independent markers of antioxidant capacity. In human placentas from normal deliveries at term substantial basal NAD(P)H activity was present. Activity was almost threefold higher in early pregnancy (P<0.0001). This was paralleled by higher total antioxidant capacity (P<0.0001), tissue glutathione concentrations (P<0.01) and gluthathione S-transferase enzyme activity (P<0.05) when compared to corresponding term placental values. NAD(P)H oxidase mediated superoxide generation could be an important modulator of the antioxidant defence response in early pregnancy.
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Affiliation(s)
- M T M Raijmakers
- MFRU, Division of Reproductive Health, Endocrinology and Development, GKT School of Medicine, St. Thomas' Hospital, London, UK.
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Brownbill P, Mahendran D, Owen D, Swanson P, Thornburg KL, Nelson DM, Sibley CP. Denudations as paracellular routes for alphafetoprotein and creatinine across the human syncytiotrophoblast. Am J Physiol Regul Integr Comp Physiol 2000; 278:R677-83. [PMID: 10712288 DOI: 10.1152/ajpregu.2000.278.3.r677] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We tested two hypotheses: 1) that fibrin-containing fibrinoid-filled denudations of the syncytiotrophoblast may provide a route for paracellular diffusion and 2) that placentas from women who had elevated maternal serum alphafetoprotein (MSAFP) in midgestation had raised permeability to AFP and greater denudation than in normal pregnancy. We measured AFP and creatinine clearance across term placental cotyledons from the above groups and used light microscope morphometric analysis to determine the volume density of fibrin-containing fibrinoid deposits. There was no significant difference between the two groups in terms of AFP and creatinine clearance or volume density of fibrin-containing fibrinoid deposits. The combined data showed a significant (P < 0.05) positive correlation between creatinine clearance, but not AFP clearance, and volume density of fibrin-containing fibrinoid. We conclude that syncytiotrophoblast denudations, with associated fibrinoid, do provide a route for diffusion of small hydrophilic solutes, but that other anatomic features of the placenta are rate limiting for transfer of AFP and similarly sized molecules.
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Affiliation(s)
- P Brownbill
- Academic Unit, St. Mary's Hospital, Manchester, M13 0JH United Kingdom
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14
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Jackson MR, Gott P, Lye SJ, Ritchie JW, Clapp JF. The effects of maternal aerobic exercise on human placental development: placental volumetric composition and surface areas. Placenta 1995; 16:179-91. [PMID: 7792281 DOI: 10.1016/0143-4004(95)90007-1] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The histomorphometry of term placentae from women who exercised regularly throughout either the first half or all of pregnancy was compared to that of placentae from matched controls to determine if regular exercise during pregnancy produced histomorphometric evidence of altered development and transport capacity. Conventional stereological techniques were used to estimate placental volumetric composition, surface areas, and villous and vascular configurations in the three groups. Exercise confined to early pregnancy increased the parenchymal component of the placenta, total vascular volume and site-specific capillary volume and surface area. Exercise throughout pregnancy increased these and multiple other histomorphometric parameters associated with the rate of placental perfusion and transfer function. However, significant changes were confined to villi > 80 microns in diameter. The localization of both the timing of the stimulus and the anatomical sites affected indicates that regular, sustained exercise modifies placental development primarily in early and mid-pregnancy. We speculate that the lack of significant changes in the structure and configuration of the smaller villi indicates that other adaptive mechanisms, such as increased rates of placental blood flow, must be well developed by the latter portion of the mid-trimester and adequately maintain fetal oxygenation and substrate delivery throughout the third trimester.
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Affiliation(s)
- M R Jackson
- Samuel Lunenfeld Research Institute, Department of Obstetrics and Gynaecology, Mount Sinai Hospital, University of Toronto, Ontario, Canada
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Larsen LG, Clausen HV, Andersen B, Graem N. A stereologic study of postmature placentas fixed by dual perfusion. Am J Obstet Gynecol 1995; 172:500-7. [PMID: 7856676 DOI: 10.1016/0002-9378(95)90563-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
OBJECTIVE Placental insufficiency has been considered the cause of increased morbidity in infants delivered postmaturely. Former quantitative studies have indicated a decrease in some placental structures just before term. In this study we describe a method of dual perfusion fixation to provide tissue for stereologic examination. Postmature placentas were examined with this method. STUDY DESIGN Eleven postmature placentas and 14 placentas delivered at term were fixed by dual perfusion. The volume and the surface area of villi, the trophoblast volume, and the volume, surface area, and length of villous capillaries were estimated by stereologic examination. The Mann-Whitney test (p < or = 0.05) was used for statistical analysis. RESULTS Morphologic features were normal in all placentas. No significant differences were disclosed in the stereologic estimates of placentas delivered at term and postmature placentas. CONCLUSION No morphologic or significant quantitative changes were found in postmature placentas.
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Affiliation(s)
- L G Larsen
- Pathological-Anatomical Institute, Herlev Hospital, Copenhagen, Denmark
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16
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Karimu AL, Burton GJ. Compliance of the human placental villus membrane at term: The concept of the fetoplacental unit as an autoregulating gas exchange system. Placenta 1994. [DOI: 10.1016/s0143-4004(05)80372-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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17
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Jackson MR, Mayhew TM, Boyd PA. Quantitative description of the elaboration and maturation of villi from 10 weeks of gestation to term. Placenta 1992; 13:357-70. [PMID: 1438084 DOI: 10.1016/0143-4004(92)90060-7] [Citation(s) in RCA: 113] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Stereological methods have been applied to a cross-sectional sample of human placentae collected at 10-41 weeks of gestation in order to provide a quantitative description of the growth and maturation of villi. Random tissue sections were analysed to derive volumes, surface areas, lengths, diameters and membrane thicknesses for villi and their fetal capillaries. Expansion of the total volume and surface area of villi can be explained by a dramatic linear growth of terminal villi which begins at about the middle of the second trimester. Growth of intermediate villi also occurs but to a more limited extent. Linear growth is accompanied by villous maturation which involves increases in the relative volume of capillaries and in villous capillarization coupled with decreases in villous diameter, capillary diameter and harmonic thickness of the villous membrane. These findings confirm that placental growth and development depend greatly on growth and maturation of terminal villi. They do not confirm sinusoidal dilation of fetal vessels as a generalized phenomenon. They also support the contention that changes in effective diffusion distances across the villous membrane have real adaptive significance.
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Affiliation(s)
- M R Jackson
- Department of Human Anatomy, University of Oxford, UK
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18
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Beck T. Placental morphometry using a computer assisted measuring programme: reference values for normal pregnancies at term. Arch Gynecol Obstet 1991; 249:135-47. [PMID: 1772266 DOI: 10.1007/bf02391580] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Using the principle that the human placenta is anatomically composed of fetomaternal flow units, we developed a computer-assisted measurement programme capable of recording complex histometric data about the characteristics of the maturation and structural differentiation of resorption villi, as well as subjecting the results to simultaneous statistical processing. Using 42 placentas obtained after normal pregnancies, reference values were derived for the five primary geometrical and six further arithmetical parameters. From these findings, we also calculated the total resorption villi surface area, the proportion of this surface area occupied by epithelial plates, and the resorption-villi surface are relative to the birth weight of the child. Our findings are compared with other available results, and the reasons for discrepancies between previously published measurements are discussed.
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Affiliation(s)
- T Beck
- Department of Obstetrics and Gynecology, University Hospital, Mainz, FRG
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Abstract
The placentae of 46 normal pregnancies artificially terminated between 6 and 15 weeks of gestation were investigated morphologically to provide trends in early villous development. Study of the specimens included phase contrast microscopic examination and histomorphometric investigation in all cases, and scanning electron microscopy in ten cases. Histomorphometric measurements included the villous barrier thickness i.e. the distance between the intervillous space and the villous capillary lumen, the trophoblastic layer thickness and the volume fraction of each villous constituents, i.e. trophoblast, stroma and capillaries. Significant negative correlations were observed between gestational age and the villous barrier and trophoblastic thickness. The data obtained were separated into two groups, embryonic (5-10 weeks) and fetal (11-15 weeks) groups, and compared. The mean barrier thickness, the mean trophoblastic thickness, the mean volume fraction for trophoblast and the sprouting-villous index were significantly greater during the embryonic period compared with the fetal period. The mean volume fraction for the stroma and for the fetal capillaries, and the mean number of capillary profiles per villous profile were significantly smaller during the embryonic period than during the fetal period. The comparison of placental histomorphometric data obtained in cases of normal early pregnancies with those observed in cases of abnormal early pregnancies could help us to elucidate the origin of anatomical and biological changes in these cases.
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Affiliation(s)
- E Jauniaux
- Histopathologic Institute, Loverval, Belgium
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Abstract
Fifty placentas were collected after vaginal delivery or cesarean section from normal and abnormal pregnancies and were fixed under different conditions of perfusion using a peristaltic roller pump. In each case a physiologic-heparin perfusate was used for less than 10 minutes, followed by a buffered solution of glutaraldehyde-formaldehyde. The best results were obtained with placentas from cesarean sections perfused immediately after delivery with a pressure maintained under 60 mm Hg. Placentas of this group were fixed within 30 minutes and electron microscopy demonstrated good preservation of cellular ultrastructure. Perfusion fixation could be performed up to 6 hours after delivery with satisfactory histologic results. In these cases, electron microscopy revealed ischemic changes 10 minutes after delivery and severe necrosis 1 hour after delivery. When the perfusion pressure was maintained over 60 mm Hg, diffuse damage of the villous morphology was observed. Histomorphometric analysis showed significant differences between terminal villi from nonperfused (immersed-fixed) placentas and perfused-fixed placentas. The mean barrier and trophoblastic thicknesses and the mean volume fraction of trophoblast were significantly (P less than .001) increased in the nonperfused group compared with the perfused group.
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Affiliation(s)
- E Jauniaux
- Department of Morbid Anatomy, King's College School of Medicine and Dentistry, Denmark Hill, London, UK
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21
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Feneley MR, Burton GJ. Villous composition and membrane thickness in the human placenta at term: a stereological study using unbiased estimators and optimal fixation techniques. Placenta 1991; 12:131-42. [PMID: 1871071 DOI: 10.1016/0143-4004(91)90017-a] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The aim of this study was to obtain unbiased estimates of in vivo villous composition and membrane thickness in the human placenta at term. By taking biopsies of the placenta 1 min after separation during caesarean section, and at regular intervals thereafter, it was possible to extrapolate back to the time zero values. It was estimated that at term intermediate and terminal villi are composed of 25.3 per cent trophoblast, 36.2 per cent stromal core and 37.1 per cent fetal capillaries. The villous membrane, defined as the outer surface of the syncytiotrophoblast (excluding the microvilli) to the inner surface of the capillary endothelium, was estimated to have an arithmetic mean thickness of 4.53 microns and a harmonic mean thickness of 3.65 microns. Villous composition and membrane thickness were found to change rapidly after delivery, despite the umbilical cord remaining clamped, and these changes were believed to be predominantly due to leakage of fetal blood or plasma from sites of damage to the villous tree caused at the time of delivery. These estimates do not, and indeed cannot, take into account the fact that the villi sampled have been removed from their uterine environment, and thus from the influences of the maternal and fetal blood pressures. However, they are free from methodological errors that have detracted from previous studies, and thus allow the morphometric diffusing capacity of the placenta at term to be calculated more accurately. They also provide baseline data against which measurements obtained from pathological pregnancies can be compared.
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Affiliation(s)
- M R Feneley
- Department of Anatomy, University of Cambridge, UK
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Burton GJ, Palmer ME, Dalton KJ. Morphometric differences between the placental vasculature of non-smokers, smokers and ex-smokers. BRITISH JOURNAL OF OBSTETRICS AND GYNAECOLOGY 1989; 96:907-15. [PMID: 2775688 DOI: 10.1111/j.1471-0528.1989.tb03344.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The aim of this study was to determine whether cigarette smoking during pregnancy has an adverse effect upon the placenta's capacity for gaseous exchange. Using recently developed stereological techniques, in conjunction with perfusion fixation, computer-assisted measurements were made on the placentas of 15 non-smokers, 15 moderate smokers, 15 heavy smokers and 13 ex-smokers, 7 of whom stopped smoking during the course of the pregnancy. Compared with the placentas of non-smokers and of those who stopped before pregnancy, it was found that the placentas of smokers and of those who stopped after conception exhibited a reduced capillary volume fraction, and an increased thickness of the villous membrane. Although they must impair gaseous exchange across the placenta, these changes were less severe than suggested by previously published reports. Nonetheless it is clear that in order to prevent these changes women should stop smoking before conception rather than during the course of a pregnancy.
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Affiliation(s)
- G J Burton
- Department of Anatomy, University of Cambridge
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23
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Burton GJ, Mayhew TM, Robertson LA. Stereological re-examination of the effects of varying oxygen tensions on human placental villi maintained in organ culture for up to 12 h. Placenta 1989; 10:263-73. [PMID: 2771896 DOI: 10.1016/0143-4004(89)90027-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The effects of exposure to various oxygen tensions on villi in organ culture are re-examined. Villi from ten normal mature placentae were cultured under hypoxic (6 per cent oxygen) and hyperoxic (40 per cent oxygen) conditions for 6 or 12 h. Control tissue (zero time in culture) was also taken. Pieces of tissue were fixed by immersion and embedded in resin for semithin sectioning. Systematically sampled microscopical fields were analysed stereologically to estimate harmonic and arithmetic mean thicknesses for the trophoblast and for the villous membrane and to assess the volumetric composition and mean diameter of villi. Trophoblast thicknesses were influenced significantly by oxygen tension, being smaller in hypoxic and greater in hyperoxic media. No significant interaction terms or effects of time in culture were detected. Villous membrane thicknesses altered in a similar fashion to trophoblast thicknesses. No significant differences in the composition of villi were detected but villi tended to be greater in diameter during hyperoxia. Findings are discussed in the context of previously reported adaptations in vivo, in different regions of the placental lobule and during chronic maternal hypoxic stress at high altitude. We conclude that there is insufficient evidence to support the claim that villi can adapt in vitro to varying ambient oxygen tensions.
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Affiliation(s)
- G J Burton
- Department of Anatomy, University of Cambridge, UK
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Mayhew TM, Burton GJ. Methodological problems in placental morphometry: apologia for the use of stereology based on sound sampling practice. Placenta 1988; 9:565-81. [PMID: 3070535 DOI: 10.1016/0143-4004(88)90001-x] [Citation(s) in RCA: 88] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Several problem areas in morphometry of human and animal placentae are reviewed. Attention is given to methods of tissue processing (handling, mode of fixation, embedding, shrinkage) and sampling (of organs, tissue blocks, sections, micrographs). Principal sources of bias and sampling variability are identified and the crucial importance of randomized sampling is emphasized. Methods for obtaining structural quantities from sections are compared. The case is made for estimating absolute values (volumes, surface areas, lengths, numbers, thicknesses) using stereological principles rather than relying on planar data (profile areas, perimeter lengths, numbers, apparent thicknesses). Absolute values may be obtained simply and efficiently without resort to expensive measuring devices. Finally, morphological descriptors suitable for correlating with functional data or for comparing normal and diseased organs are surveyed.
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Affiliation(s)
- T M Mayhew
- Department of Anatomy, Marischal College, University of Aberdeen, UK
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Abstract
Perfusion fixation can redilate the fetal capillary network of the freshly delivered human placenta to its in vivo dimensions. As part of the fixation procedure in earlier experiments a venous back-pressure of 20 mmHg was applied on the rationale that this was necessary for full distension of the fetal capillaries. In order to verify this assertion, five mature placentae were fixed by perfusion fixation but without the application of such a back-pressure. No statistically significant difference was found between the values for the various parameters measured in placentae fixed in this manner compared with those processed using the original technique. In view of this finding, and of the implication that impedence to venous flow may cause fetomaternal fluid shift during in vitro perfusion experiments, it would appear that venous back-pressure should best be omitted from the perfusion fixation technique. The shrinkage rate associated with this technique was found to be approximately 2.0 per cent, based on the measurement of maternal erythrocyte diameters.
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Affiliation(s)
- G J Burton
- Department of Anatomy, University of Cambridge, UK
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