Villous Tree Research Articles

A step to step guide to novel 3D microscopic topologic analysis of villous trees of human placentas

A step to step guide to novel 3D microscopic topologic analysis of villous trees of human placentas

<I>Ex Vivo</I> Delineation of the Human Placental Vasculature via Three-Dimensional Computed Tomography Angiography of Placental Villous Trees

<I>Ex Vivo</I> Delineation of the Human Placental Vasculature via Three-Dimensional Computed Tomography Angiography of Placental Villous Trees

A multiscale model of placental oxygen exchange: The effect of villous tree structure on exchange efficiency

The placenta is critical to fetal health during pregnancy as it supplies oxygen and nutrients to maintain life. It has a complex structure, and alterations to this structure across spatial scales are associated with several pregnancy complications, including intrauterine growth restriction (IUGR). The relationship between placental structure and its efficiency as an oxygen exchanger is not well understood in normal or pathological pregnancies. Here we present a computational framework that predicts oxygen transport in the placenta which accounts for blood and oxygen transport in the space around a placental functional unit (the villous tree). The model includes the well-defined branching structure of the largest villous tree branches, as well as a smoothed representation of the small terminal villi that comprise the placenta's gas exchange interfaces. The model demonstrates that oxygen exchange is sensitive to villous tree geometry, including the villous branch length and volume, which are seen to change in IUGR. This is because, to be an efficient exchanger, the architecture of the villous tree must provide a balance between maximising the surface area available for exchange, and the opposing condition of allowing sufficient maternal blood flow to penetrate into the space surrounding the tree. The model also predicts an optimum oxygen exchange when the branch angle is 24 °, as villous branches and TBs are spread out sufficiently to channel maternal blood flow deep into the placental tissue for oxygen exchange without being shunted directly into the DVs. Without concurrent change in the branch length and angles, the model predicts that the number of branching generations has a small influence on oxygen exchange. The modelling framework is presented in 2D for simplicity but is extendible to 3D or to incorporate the high-resolution imaging data that is currently evolving to better quantify placental structure.

Functional morphology of the placental villous tree at term singleton pregnancies, achieved by methods of assisted reproductive technology

Introduction. Of special interest in the use of assisted reproductive technology techniques (ART) is the placenta as the main authority responsible for the formation and growth of the fetus. Purpose and objectives. The aim of our research is to study the morpho-functional state of placenta after pregnancy achieved by means of ART. Research objectives: histological and immunohistochemical study using the CD34, NOS-3 and HIF in these placentas. Methods. Total 98 placentas from full-term singleton pregnancies with gestational age were examined. Two study groups were formed: a basic group - the placenta from pregnancy induced methods of ART (n = 60) was divided into I subgroup, which included 30 placentas from women with primary infertility and II subgroup - 30 placentas from women with secondary infertility comparison group consisted of the placenta from the naturally ensuing pregnancy (12 placentas from primigravidae and 26 placentas from multiparous patients). Results. Histological examination of the morphological structure of the placenta was found that the incidence of chronic placental insufficiency was 1.4 times higher than in the subgroup with secondary infertility. Immunohistochemical study of placentas in the basic group, there was a significant decrease in the expression of cell adhesion marker (CD34) in the vascular epithelium chorionic villi, decreased expression of vascular tone marker (NOS-3) and increase the expression of hypoxia-inducible factor (HIF-1α) in the basic group compared to placenta s from children born naturally. Changes in the expression of the studied markers are most pronounced in the placentas from children born with secondary infertility, which is likely due to the high incidence of inflammatory diseases of the pelvic organs in this subgroup. Conclusions. Endometrial pathology in primary and secondary infertility, can cause the formation of functional disorders and morphological structure of placental complex and occurrence in the future placental insufficiency.

The Tree(s) of Life: The Human Placenta and My Journey to Learn More about It.

The Tree(s) of Life: The Human Placenta and My Journey to Learn More about It.

Novel 3D light microscopic analysis of IUGR placentas points to a morphological correlate of compensated ischemic placental disease in humans.

The villous tree of the human placenta is a complex three-dimensional (3D) structure with branches and nodes at the feto-maternal border in the key area of gas and nutrient exchange. Recently we introduced a novel, computer-assisted 3D light microscopic method that enables 3D topological analysis of branching patterns of the human placental villous tree. In the present study we applied this novel method to the 3D architecture of peripheral villous trees of placentas from patients with intrauterine growth retardation (IUGR placentas), a severe obstetric syndrome. We found that the mean branching angle of branches in terminal positions of the villous trees was significantly different statistically between IUGR placentas and clinically normal placentas. Furthermore, the mean tortuosity of branches of villous trees in directly preterminal positions was significantly different statistically between IUGR placentas and clinically normal placentas. We show that these differences can be interpreted as consequences of morphological adaptation of villous trees between IUGR placentas and clinically normal placentas, and may have important consequences for the understanding of the morphological correlates of the efficiency of the placental villous tree and their influence on fetal development.

A three-dimensional culture system recapitulates placental syncytiotrophoblast development and microbial resistance.

In eutherians, the placenta acts as a barrier and conduit at the maternal-fetal interface. Syncytiotrophoblasts, the multinucleated cells that cover the placental villous tree surfaces of the human placenta, are directly bathed in maternal blood and are formed by the fusion of progenitor cytotrophoblasts that underlie them. Despite their crucial role in fetal protection, many of the events that govern trophoblast fusion and protection from microbial infection are unknown. We describe a three-dimensional (3D)-based culture model using human JEG-3 trophoblast cells that develop syncytiotrophoblast phenotypes when cocultured with human microvascular endothelial cells. JEG-3 cells cultured in this system exhibit enhanced fusogenic activity and morphological and secretory activities strikingly similar to those of primary human syncytiotrophoblasts. RNASeq analyses extend the observed functional similarities to the transcriptome, where we observed significant overlap between syncytiotrophoblast-specific genes and 3D JEG-3 cultures. Furthermore, JEG-3 cells cultured in 3D are resistant to infection by viruses and Toxoplasma gondii, which mimics the high resistance of syncytiotrophoblasts to microbial infections in vivo. Given that this system is genetically manipulatable, it provides a new platform to dissect the mechanisms involved in syncytiotrophoblast development and microbial resistance.

CLINICAL AND MORPHOLOGICAL CHARACTERIZATION OF FETOPLACENTAL COMPLEX IN PREGNANT PATIENTS WITH DIFFUSE TOXIC GOITER

Актуальность. Течение беременности и родов у пациенток с диффузным токсическим зобом (ДТЗ) часто осложняется преэклампсией, фетоплацентарной недостаточностью, преждевременной отслойкой плаценты, сопряжено с повышенной материнской и перинатальной смертностью.

Sensitivity to the thromboxane A2 analog U46619 varies with inner diameter in human stem villous arteries

IntroductionThe vascular resistance of stem villous arteries is determined by the balance between different contractile and relaxant agents and in the utero-placental circulation. Thromboxane A2 (TxA2), prostaglandin F2α (PGF2α) and endothelin-1 (ET-1) are considered to be among the most important contractile factors. However, it is not known if their contractile effects are consistent along the villous tree. We hypothesized that the sensitivity to different agonists could be influenced by artery diameter and thus that their contribution to placental vascular resistance may differ. MethodsUsing an isometric wire myograph, the contractility and sensitivity (pD2) to the thromboxane A2 mimetic U46619, PGF2α and ET-1 were investigated in isolated human stem villous arteries and human uterine fundus and isthmus arteries obtained from healthy, pregnant women who had experienced uncomplicated pregnancy. ResultsIn fetal arteries, the pD2 values for U46619 correlated positively with arterial diameter with no such dependence observed for ET-1 and PGF2α. In maternal arteries, pD2 remained constant for all the agonists tested despite highly variable vessel diameter. DiscussionA selective decrease in sensitivity to TxA2 receptor stimulation was observed with decreasing vascular diameter in human stem villous arteries. The contractile factors PGF2α and ET-1 show no such relationship.

The basal chorionic trophoblast cell layer: An emerging coordinator of placenta development.

During gestation, fetomaternal exchange occurs in the villous tree (labyrinth) of the placenta. Development of this structure depends on tightly coordinated cellular processes of branching morphogenesis and differentiation of specialized trophoblast cells. The basal chorionic trophoblast (BCT) cell layer that localizes next to the chorioallantoic interface is of critical importance for labyrinth morphogenesis in rodents. Gcm1-positive cell clusters within this layer initiate branching morphogenesis thereby guiding allantoic fetal blood vessels towards maternal blood sinuses. Later these cells differentiate and contribute to the syncytiotrophoblast of the fetomaternal barrier. Additional cells within the BCT layer sustain continued morphogenesis, possibly through a repopulating progenitor population. Several mouse mutants highlight the importance of a structurally intact BCT epithelium, and a growing number of studies addresses its patterning and epithelial architecture. Here, we review and discuss emerging concepts in labyrinth development focussing on the biology of the BCT cell layer.

Features of morphological and spatial structure of placenta at in the antenatal fetal hypoxia

The paper outlines results of morphological study of 55 placentas of fetuses died of antenatal hypoxia, in comparison with the results of the original X-ray micro- tomography of the placenta. Identified two subgroups of antenatal losses other than the maturity of the villi, and spatial localization of vasculopathy structural organization. It was revealed the features of the three-dimensional structure of the placenta during antenatal hypoxia with fetal loss, depending on the maturity of the villous tree.

Placental morphology in pregnancies associated with pregravid obesity

Objective: Pre-gravid obesity is associated with increased morbidity and mortality for both mother and offspring. We aimed to investigate the changes in placental structure and to characterize the placental inflammatory status in obese women.Methods: Placentas from 10 women with pregravid body mass index ≥ 30 kg/m2 were analyzed histopathologically and compared with those from 10 normal weight women. The effect of pregravid obesity on placental structure was investigated by examining placental maturity, angiogenesis, inflammatory response, and vascular abnormalities. Hematoxylin and eosin stain, immunohistochemical analysis, and morphometric analysis were performed.Results: Immaturity of the villous tree was demonstrated more often in the pregravid obesity group (p = 0.005). The villous tree was mainly represented by villi of larger diameter (p = 0.001) and lower number (p = 0.023) compared with controls. By contrast, the number of capillaries per villus was increased in the obese group (p = 0.001), while the global number of capillaries per surface unit did not differ in the studied groups (p = 1). There was no difference between the pre-gravid obese group and controls in inflammatory status and vascular pathology.Conclusions: Pregravid obesity is associated with focal immaturity of the villous tree and angiogenetic abnormalities of the placenta.

Does 2D-Histologic identification of villous types of human placentas at birth enable sensitive and reliable interpretation of 3D structure?

IntroductionThe villous tree of human placentas is a complex three-dimensional (3D) structure which enables fetomaternal exchange. Current concepts of microscopic analyses are based on the analysis of two-dimensional (2D) histologic sections. For this approach, the assessment of the stromal core of sectioned villi is of key importance. The classification of stromal properties of sectioned villi allows allocation of villous sections to villous types which are named by their expected position in villous trees (terminal, intermediate, and stem villi). MethodThe present study takes these current concepts of placental histology as hypothesis and validates them against predetermined 3D positions of branches of villous trees. The 3D positions were determined prior to histologic sectioning using a recently introduced 3D-microscopic approach. Individual histologic sections of villi were classified by their stromal structures and inter rater variability of these histologic assessments were determined. Results/disscussionInter rater variability was high and indicates substantial observer influence on the outcome of histologic assessments. Cross-match of villous types with the predetermined positions of villous branches of villous trees revealed substantial mismatch between the outcome of stromal classification and 3D-position of the sectioned villi in the placental villous trees.

Fetal Thrombotic Vasculopathy

AbstractFetal thrombotic vasculopathy (FTV) is the term used to encompass the histologic findings identified in placentas with fetal thrombotic lesions: occlusive and nonocclusive chorionic vessel thrombi, avascular villi in the distribution of a single villous tree, intramural vascular fibrin, and hemorrhagic endovasculitis. The underlying etiology of FTV is largely unknown though hypercoagulability and circulatory stasis have been the main focuses in the literature to explain the hemostatic abnormalities. This article reviews the literature in both defining and discussing, potential etiologies of FTV, as well as neonatal outcomes.

Different epigenetic states define syncytiotrophoblast and cytotrophoblast nuclei in the trophoblast of the human placenta

IntroductionThe syncytiotrophoblast (STB) epithelial covering of the villous tree in the human placenta is a multi-nucleated syncytium that is sustained by continuous incorporation of differentiating cytotrophoblast (CTB) cells. STB nuclei display a variety of morphologies, but are generally more condensed in comparison to CTB nuclei. Here, we consider whether this condensation is a feature of epigenetic regulation of chromatin structure. MethodsSemi-quantitative immunohistochemical investigations of a panel of histone modifications were performed to determine the relative proportions in CTB and STB nuclear populations. We also investigated the patterns of DNA methylation and distribution of DNA methyltransferases enzymes in these populations. ResultsUnexpectedly DNA methylation, and H3K9me3 and H3K27me3, which are modifications associated with heterochromatin, are present at lower levels in STB nuclei compared to CTB, despite the intensive condensation in the former nuclear population and the progenitor state of the latter. By contrast, STB nuclei are enriched for H4K20me3, which is also associated with repressive states. 5'hydroxymethylcytosine immunoreactivity is higher in STB, with intense staining observed in the highly condensed nuclei within syncytial knots. DiscussionCell-type specific epigenetic states exist within the trophoblast populations potentially regulating their different functions and developmental properties and suggesting non-canonical epigenetic states associated with the properties of these cells.

Alpha-1-Antitrypsin: A Novel Human High Temperature Requirement Protease A1 (HTRA1) Substrate in Human Placental Tissue

The human serine protease high temperature requirement A1 (HTRA1) is highly expressed in the placental tissue, especially in the last trimester of gestation. This suggests that HTRA1 is involved in placental formation and function. With the aim of a better understanding of the role of HTRA1 in the placenta, candidate substrates were screened in a placenta protein extract using a gel-based mass spectrometric approach. Protease inhibitor alpha-1-antitrypsin, actin cytoplasmic 1, tropomyosin beta chain and ten further proteins were identified as candidate substrates of HTRA1. Among the identified candidate substrates, alpha-1-antitrypsin (A1AT) was considered to be of particular interest because of its important role as protease inhibitor. For investigation of alpha-1-antitrypsin as substrate of HTRA1 synthetic peptides covering parts of the sequence of alpha-1-antitrypsin were incubated with HTRA1. By mass spectrometry a specific cleavage site was identified after met-382 (AIPM382↓383SIPP) within the reactive centre loop of alpha-1-antitrypsin, resulting in a C-terminal peptide comprising 36 amino acids. Proteolytic removal of this peptide from alpha-1-antitrypsin results in a loss of its inhibitor function. Beside placental alpha-1-antitrypsin the circulating form in human plasma was also significantly degraded by HTRA1. Taken together, our data suggest a link between the candidate substrates alpha-1-antitrypsin and the function of HTRA1 in the placenta in the syncytiotrophoblast, the cell layer attending to maternal blood in the villous tree of the human placenta. Data deposition: Mass spectrometry (MS) data have been deposited to the ProteomeXchange with identifier PXD000473.

Novel and efficient 3D microscopic analysis of isolated villous trees of human placentas

The villous trees of human placentas delineate the fetomaternal border and are complex three-dimensional structures. Thus far, they are primarily analyzed from thin two-dimensional histological sections. Such sections cannot provide access to key aspects like branching nodes and branch order. As a consequence, histologic nomenclature of the villous tree does not include characterization of villous nodes. Using samples taken from 50 normal human placentas at birth, in the present study, we show that analysis procedures for the three-dimensional reconstruction of neuronal dendrite trees can also analyze villous trees of human placentas. We demonstrate how parameters of dendrite analysis can be adapted to the analysis of villous trees. Nodes and their branches (e.g., branching hierarchy, branching angles, diameters and lengths of branches) can be efficiently measured in whole-mount preparations of isolated villous trees using high-end light microscopy. Nodes are classified according to their distance from the terminal end of the villous trees. These novel data differ qualitatively from the data obtainable from histological sections and supplement such data. Since this novel method can be applied conveniently, an effective and technically feasible access to three-dimensional morphology of villous trees is opened.

Novel 3D microscopic analysis of human placental villous trees reveals unexpected significance of branching angles.

The villous trees of human placentas delineate the fetomaternal border and are complex three-dimensional (3D) structures. Thus far, they have primarily been analyzed as thin, two-dimensional (2D) histological sections. However, 2D sections cannot provide access to key aspects such as branching nodes and branch order. Using samples taken from 50 normal human placentas at birth, in the present study we show that analysis procedures for 3D reconstruction of neuronal dendritic trees can also be used for analyzing trees of human placentas. Nodes and their branches (e.g., branching hierarchy, branching angles, diameters, and lengths of branches) can be efficiently measured in whole-mount preparations of isolated villous trees using high-end light microscopy. Such data differ qualitatively from the data obtainable from histological sections and go substantially beyond the morphological horizon of such histological data. Unexpectedly, branching angles of terminal branches of villous trees varied inversely with the fetoplacental weight ratio, a widely used clinical parameter. Since branching angles have never before been determined in the human placenta, this result requires further detailed studies in order to fully understand its impact.

Y.W. Loke, Life's Vital Link: The Astonishing Role of the Placenta

Y.W. Loke, Life's Vital Link: The Astonishing Role of the Placenta

Analysis of syncytial nuclear aggregates in preeclampsia shows increased sectioning artefacts and decreased inter-villous bridges compared to healthy placentas

Syncytial nuclear aggregates (SNAs) are increased in pregnancy complications and include ‘true’ syncytial knots and inter-villous bridges. Apparent nuclear overlay caused by sectioning artefacts are frequently counted from single sections. Haematoxylin and eosin stained serial sections were assessed for frequency of SNA subtypes in placentas from normal, preeclamptic and fetal growth restricted (FGR) pregnancies. There were more sectioning artefacts and syncytial knots and fewer bridges in samples from preeclampsia compared to controls. There were no significant differences between FGR and control samples. This suggests the villous tree in preeclampsia has less inherent structural support and trophoblast cell dynamics are different.