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Gynecologie, Obstetrique & Fertilite Jun 2010Determination of mechanical properties of human placenta.
OBJECTIVES
Determination of mechanical properties of human placenta.
PATIENTS AND METHODS
Realisation of an experimental study using 80 human placentas and modelisation of this study using a finite element numerical model. Using the inverse analysis method, research of the parameters of placenta's behavior.
RESULTS
Hyper-Visco-Elastic law written by Ogden, optimized for placenta with parameters: mu(1)=0.0001881Mpa, mu(2)=-0.000240Mpa, mu(3)=mu(4)=0Mpa and alpha(1)=2, alpha(2)=-8, alpha(3)=alpha(4)=0 in static condition.
DISCUSSION AND CONCLUSION
The parameters enable an approach of the mechanical behavior of the placenta. They could be used in numerical modelisation.
Topics: Adult; Biomechanical Phenomena; Elasticity; Female; Gestational Age; Humans; Placenta; Pregnancy; Viscosity
PubMed: 20576559
DOI: 10.1016/j.gyobfe.2010.04.012 -
Animal Reproduction Science Jul 2004Afrotheria, one of four mammalian superorders, comprises elephants, sea cows, hyraxes, aardvark, elephant shrews, tenrecs and golden moles. Their placentas either form... (Comparative Study)
Comparative Study Review
Afrotheria, one of four mammalian superorders, comprises elephants, sea cows, hyraxes, aardvark, elephant shrews, tenrecs and golden moles. Their placentas either form an equatorial band or are discoid in shape. The interhemal region, separating fetal and maternal blood, is endotheliochorial in elephants, aardvark and possibly the sea cows, but hemochorial in the remaining orders. There is a secondary epitheliochorial placenta in elephant shrews while a similar structure in tenrecs erodes maternal tissues. Specialized hemophagous regions are a striking characteristic of some of these placentas yet absent in hyraxes, elephant shrews, and golden moles. It is possible that the common ancestor of the Afrotheria had an endotheliochorial placenta. Establishment of a hemochorial condition, as seen in rock hyraxes, elephant shrews, tenrecs, and golden moles, would be a more recent development. The elephant, manatee, and aardvark all have circumferential placentas. Thus the formation of a discoid placenta with a more or less extensive secondary placenta in elephant shrews and tenrecs would also be a derived state.
Topics: Animals; Biological Evolution; Dugong; Elephants; Eulipotyphla; Female; Hyraxes; Mammals; Moles; Placenta; Placentation; Pregnancy; Shrews; Xenarthra
PubMed: 15271442
DOI: 10.1016/j.anireprosci.2004.04.018 -
Ultrasound in Medicine & Biology May 2019Attenuation coefficient estimation has the potential to be a useful tool for placental tissue characterization. A current challenge is the presence of inhomogeneities in...
Attenuation coefficient estimation has the potential to be a useful tool for placental tissue characterization. A current challenge is the presence of inhomogeneities in biological tissue that result in a large variance in the attenuation coefficient estimate (ACE), restricting its clinical utility. In this work, we propose a new Attenuation Estimation Region Of Interest (AEROI) selection method for computing the ACE based on the (i) envelope signal-to-noise ratio deviation and (ii) coefficient of variation of the transmit pulse bandwidth. The method was first validated on a tissue-mimicking phantom, for which an 18%-21% reduction in the standard deviation of ACE and a 14%-24% reduction in the ACE error, expressed as a percentage of reported ACE, were obtained. A study on 59 post-delivery clinically normal placentas was then performed. The proposed AEROI selection method reduced the intra-subject standard deviation of ACE from 0.72 to 0.39 dB/cm/MHz. The measured ACE of 59 placentas was 0.77 ± 0.37 dB/cm/MHz, which establishes a baseline for future studies on placental tissue characterization.
Topics: Adult; Female; Humans; Middle Aged; Placenta; Pregnancy; Reference Values; Signal Processing, Computer-Assisted; Ultrasonography; Young Adult
PubMed: 30685076
DOI: 10.1016/j.ultrasmedbio.2018.10.015 -
Environmental Pollution (Barking, Essex... Jan 2020The placenta is essential for sustaining the growth of the fetus. The aim of this study was to investigate the role of the placenta in MCLR-induced significant reduction...
The placenta is essential for sustaining the growth of the fetus. The aim of this study was to investigate the role of the placenta in MCLR-induced significant reduction in fetal weight, especially the changes in placental structure and function. Pregnant mice were intraperitoneally injected with MCLR (5 or 20 μg/kg) from gestational day (GD) 13 to GD17. The results showed MCLR reduced fetal weight and placenta weight. The histological specimens of the placentas were taken for light and electron microscopy studies. The internal space of blood vessels decreased obviously in the placental labyrinth layer of mice treated with MCLR. After the ultrastructural examination, the edema and intracytoplasmic vacuolization, dilation of the endoplasmic reticulum and corrugation of the nucleus were observed. In addition, maternal MCLR exposure caused a reduction of 11β-hydroxysteroid dehydrogenase type 2 (HSD11B2) expression in placentae, a critical regulator of fetal development. Several genes of placental growth factors, such as Vegfα and Pgf and several genes of nutrient transport pumps, such as Glut1 and Pcft were depressed in placentas of MCLR-treated mice, however nutrient transporters Fatp1 and Snat4 were promoted. Moreover, significant increases in malondialdehyde (MDA) revealed the occurrence of oxidative stress caused by MCLR, which was also verified by remarkable decrease in the glutathione levels, total antioxidant capacity (T-AOC) as well as the activity of antioxidant enzymes. Real-time PCR and western blot analysis revealed that GRP78, CHOP, XBP-1, peIF2α and pIRE1 were remarkable increased in placentas of MCLR-treated mice, indicating that endoplasmic reticulum (ER) stress pathway was activated by MCLR. Furthermore, oxidative stress and ER stress consequently triggered apoptosis which contributed to the impairment of placental development. Collectively, these results suggest maternal MCLR exposure results in reduced fetal body weight, which might be associated with ROS-mediated endoplasmic reticulum stress and impairment in placental structure and function.
Topics: Animals; Apoptosis; Endoplasmic Reticulum Chaperone BiP; Endoplasmic Reticulum Stress; Female; Fetal Development; Fetal Weight; Gestational Age; Marine Toxins; Maternal Exposure; Mice; Mice, Inbred ICR; Microcystins; Placenta; Pregnancy; Reactive Oxygen Species
PubMed: 31672369
DOI: 10.1016/j.envpol.2019.113362 -
Journal of Biomechanics Jan 2016Intrauterine Growth Restriction (IUGR) is a disease where the placenta is unable to transfer enough nutrients to the fetus, limiting its growth, and resulting in high...
BACKGROUND
Intrauterine Growth Restriction (IUGR) is a disease where the placenta is unable to transfer enough nutrients to the fetus, limiting its growth, and resulting in high mortality and life-long morbidities. Current detection rates of IUGR are poor, resulting in limited disease management. Elastography is a promising non-invasive tool for the detection of IUGR, and works by detecting changes in the mechanical properties of the placenta. To date, however, it is not known whether IUGR placentas have different mechanical properties from normal ones, and thus investigating this is the first focus of the current study. The second focus is to evaluate and model the viscoelastic properties of the normal and IUGR placenta, so that it may be possible to improve elastography in the future by incorporating viscoelasticity.
METHODS
Cyclic uniaxial mechanical compression testing was conducted on post-delivery human placenta samples. 18 samples from 5 normal placentae and 12 samples from 3 IUGR placentae were tested. Viscoelastic models were fitted to the resulting experimental data.
RESULTS
Mechanical testing showed that IUGR placentae have reduced stiffness and viscosity compared to normal placentae. Linear viscoelastic models were unable to provide a good fit to the data, but non-linear viscoelastic solid (NVS) models could do so. The best performing model was a five parameters bi-exponential NVS model. Two of the five parameters appear to capture the differences between normal and diseased samples.
DISCUSSION
Our results demonstrate that IUGR placentae have different mechanical properties from normal placentae, and a five parameter bi-exponential NVS model can effectively describe the mechanical properties of the placenta in health and disease.
Topics: Elasticity; Elasticity Imaging Techniques; Female; Fetal Growth Retardation; Humans; Models, Biological; Placenta; Pregnancy; Viscosity
PubMed: 26708966
DOI: 10.1016/j.jbiomech.2015.11.055 -
Placenta 1983Different morphometric parameters have been applied to the study of the morphological differences between a group of normal placentae and a group of placentae collected...
Different morphometric parameters have been applied to the study of the morphological differences between a group of normal placentae and a group of placentae collected from Class B diabetic mothers. The placentae of the diabetics were divided in two groups based on the growth characteristics and neonatal outcome of the infants at birth. It has been shown that the placentae of the appropriate for gestational age infants were morphologically very similar to the control group except for a well-developed villous vascularization. In contrast, the placentae of the large for gestational age infants were shown to differ from the controls by having heavier placentae due mainly to a significant accumulation of non-parenchyma and a moderate increase in parenchymal tissue. Consequently, although there was significantly more villous tissue in these placentae, the surface areas of exchange between mother and fetus in terms of capillary and villous surface areas were only moderately enlarged due to a relatively lower number of villi containing non-parenchymal tissue. However, on a functional basis, despite these morphological differences, the results of this study suggest that placental function is not adversely affected in Class B diabetics, and the perinatal morbidity associated with this condition is probably the result of metabolic abnormalities present in the mother and the fetus.
Topics: Adult; Birth Weight; Chorionic Villi; Diabetes Mellitus; Female; Gestational Age; Humans; Infant, Newborn; Organ Size; Placenta; Pregnancy; Pregnancy in Diabetics; Trophoblasts
PubMed: 6856585
DOI: 10.1016/s0143-4004(83)80012-5 -
The Kobe Journal of Medical Sciences Aug 1989An investigation was done to clarify the pathological background of pre-eclampsia. Thirty four placentae were studied immunopathologically in comparison to control...
An investigation was done to clarify the pathological background of pre-eclampsia. Thirty four placentae were studied immunopathologically in comparison to control cases. The results showed slightly positive stains of hCG containing alpha- and beta-subunits in syncytiocytotrophoblastic layers especially in severe pre-eclampsia cases. The placentae in mild pre-eclampsia showed only weakly and partly positive by those stains. Other control cases were negative except earlier abortion ones. No any positive stains of hCG series could be seen in two placentas from mothers with spontaneous hypertension. Stains by hPL and SP 1 were all positive and increased gradually in their staining pattern and degree from early pregnancy toward term. It supports the findings that maternal serum hCG series increased slightly in pre-eclampsia and that those changes might occur before clinical onset of pre-eclampsia. Then, the placenta has an important role in developing pre-eclampsia.
Topics: Antibodies, Monoclonal; Chorionic Gonadotropin; Female; Humans; Immunohistochemistry; Peroxidases; Placenta; Pre-Eclampsia; Pregnancy
PubMed: 2636286
DOI: No ID Found -
Physiological Research 2001The impact of environmental pollution at the place of residence of pregnant women and of their smoking habits on the cellular energy metabolism of placental tissue was...
The impact of environmental pollution at the place of residence of pregnant women and of their smoking habits on the cellular energy metabolism of placental tissue was investigated. Samples of full-term placentas were randomly collected from two environmentally different regions of Slovakia (Bratislava, Stará Lubovna) and the activity of lactate dehydrogenase (LDH) was measured. Our results showed enhanced LDH activity in the placenta that was dependent on both the type of environmental pollutants at the place of residence and the smoking habits during pregnancy. The enhanced LDH activity may reflect hypoxic conditions due to the accumulation of heavy metals and toxic compounds of tobacco smoke in the placental tissue. A high content of heavy metal particles, found in placental samples from Stará Lubovna in our previous studies, might contribute to the increased LDH activity in placentas from this region. We hypothesize that fine metal particles deposited in the placental tissue might be phagocytozed by the syncytiotrophoblast, thus contributing to the decreased oxygen level in placental tissue.
Topics: Environmental Pollutants; Female; Humans; L-Lactate Dehydrogenase; Metals, Heavy; Placenta; Pregnancy; Slovakia; Smoking
PubMed: 11702858
DOI: No ID Found -
The American Journal of Pathology Dec 2000The role of placenta in vertical transmission is not yet fully understood. A protective role of the placenta during gestation is suggested by the finding that caesarian...
The role of placenta in vertical transmission is not yet fully understood. A protective role of the placenta during gestation is suggested by the finding that caesarian sections reduce the risk of transmission of human immunodeficiency virus (HIV)-1 from mother to child three- to fourfold. Here we investigated whether the immunological milieu of the placenta might be important in HIV-1 transmission. In situ imaging of immunohistochemically stained placenta sections and reverse transcriptase-polymerase chain reaction demonstrated a fourfold increase in CCR5:CXCR4 expression ratio in placentae from transmitting women compared to placentae from nontransmitting women. This chemokine receptor repertoire was consistent with an up-regulation of interleukin-4 and interleukin-10 expression in placentae from nontransmitting placentae compared to transmitting placentae. In situ imaging demonstrated that CCR5 and CXCR4 were expressed on placental macrophages and lymphocytes but not in trophoblasts. Simultaneous immunofluorescence/ultrasensitive in situ hybridization for HIV-1 gag-pol mRNA revealed that HIV-1 infects primarily CXCR4-expressing cells in placentae from nontransmitting women whereas predominantly CCR5-expressing cells were infected in placentae from transmitting women. These data are consistent with transmission of a homogeneous population of nonsyncytium-inducing HIV-1 isolates that use CCR5 as co-receptor.
Topics: Cytokines; Female; HIV Infections; HIV-1; Humans; Infectious Disease Transmission, Vertical; Placenta; Receptors, CCR5; Receptors, CXCR4; Up-Regulation
PubMed: 11106553
DOI: 10.1016/S0002-9440(10)64819-5 -
Biology of the Neonate 1975The presence of two types of cells with IgG surface receptors was demonstrated in mature and immature human placentas. One type corresponded morphologically to the...
The presence of two types of cells with IgG surface receptors was demonstrated in mature and immature human placentas. One type corresponded morphologically to the Hofbauer cells and the second to the blood monocytes. Transitional forms between monocytes and Hofbauer cells were also observed.
Topics: Candida albicans; Female; Humans; Immunoglobulin G; Monocytes; Phagocytosis; Placenta; Pregnancy; Receptors, Drug
PubMed: 1093573
DOI: 10.1159/000240738