SBF SEM of Human term placental villi
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ABSTRACT:
SUBMITTER: Rohan Lewis
PROVIDER: EMPIAR-10967 | biostudies-other |
REPOSITORIES: biostudies-other
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Project description:1. Glucose phosphorylation rates of about 1 mumole/g./min. have been measured at room temperature in homogenates of human placental chorionic villi, and these rates are relatively constant throughout gestation. 2. This reaction has an apparent K(m) for glucose of 3x10(-5)m both in early and term placenta. 3. Human foetal membranes, the amnion and chorion, also phosphorylate glucose at a rate about equal to that of the placenta. 4. On incubation of intact bits of villus tissue from 8-12-week or full-term placenta with labelled pyruvate, followed by paper chromatography of the tissue extract, the following distribution of label was observed: residual pyruvate, 40-60%; lactate, 30-50%; glucose, 6%; fructose, 7%; sorbitol, 0.6%. 5. The concept of the placenta acting as a foetal liver during early pregnancy is inconsistent with the observation that glucose production by this organ persists up to term.
| S-EPMC1270392 | biostudies-other
Project description:Maintenance of a healthy pregnancy is reliant on a successful balance between the fetal and maternal immune systems. Although the maternal mechanisms responsible have been well studied, those used by the fetal immune system remain poorly understood. Using suspension mass cytometry and various imaging modalities, we report a complex immune system within the mid-gestation (17-23 weeks) human placental villi (PV). Consistent with recent reports in other fetal organs, T cells with memory phenotypes, although rare in abundance, were detected within the PV tissue and vasculature. Moreover, we determined that T cells isolated from PV samples may be more proliferative after T cell receptor stimulation than adult T cells at baseline. Collectively, we identified multiple subtypes of fetal immune cells within the PV and specifically highlight the enhanced proliferative capacity of fetal PV T cells.
| S-EPMC8935213 | biostudies-literature
Project description:BACKGROUND: During human pregnancy, the placental villi produces high amounts of estradiol. This steroid is secreted by the syncytium, which is directly in contact with maternal blood. Estradiol has to cross placental foetal vessels to reach foetal circulation. The enzyme 17beta-hydroxysteroid dehydrogenase type 2 (17beta-HSD2) was detected in placental endothelial cells of foetal vessels inside the villi. This enzyme catalyzes the conversion of estradiol to estrone, and of testosterone to androstenedione. It was proposed that estradiol level into foetal circulation could be regulated by 17beta-HSD2. METHODS: We obtained placentas from 10 to 26 6/7 weeks of pregnancy from women undergoing voluntary termination of pregnancy, term placentas were collected after normal spontaneous vaginal deliveries. We quantified 17beta-HSD2 mRNA levels in mid-gestation and term human placenta by RT-QPCR. We produced a new anti-17beta-HSD2 antibody to study its spatio-temporal expression by immunohistochemistry. We also compared steroid levels (testosterone, estrone and estradiol) and 17beta-HSD2 mRNA and protein levels between term placenta and endometrium. RESULTS: High 17beta-HSD2 mRNA and protein levels were found in both mid-gestation and term placentas. However, we showed that 17beta-HSD2 mRNA levels increase by 2.27 fold between mid-gestation and term. This period coincides with a transitional phase in the development of the villous vasculature. In mid-gestation placenta, high levels of 17beta-HSD2 were found in mesenchymal villi and immature intermediate villi, more precisely in endothelial cells of the stromal channel. At term, high levels of 17beta-HSD2 were found in the numerous sinusoidal capillaries of terminal villi. 17beta-HSD2 mRNA and protein levels in term placentas were respectively 25.4 fold and 30 to 60 fold higher than in the endometrium. Steroid levels were also significantly higher in term placenta than in the endometrium. CONCLUSION: The spatial and temporal expression of 17beta-HSD2 in the placenta during pregnancy and the comparison of 17beta-HSD2 expression and steroid levels between placental villi and endometrium are compatible with a role in the modulation of active and inactive forms of estrogens. Our observations strongly support the hypothesis that 17beta-HSD2 acts as a barrier decreasing estradiol secretion rates in the foetal circulation.
| S-EPMC1947994 | biostudies-literature
Project description:Placental function is essential for fetal development and establishing the foundations for lifelong health. The placental villous stroma is a connective tissue layer that supports the fetal capillaries and villous trophoblast. All the nutrients that cross the placenta must also cross the stroma, and yet little is known about this region. This study uses high-resolution three-dimensional imaging to explore the structural complexity of this region within the placental villi. Serial block-face scanning electron microscopy and confocal microscopy were used to image the placental villous stroma in three-dimensions. Transmission electron microscopy (TEM) was used to generate high resolution two-dimensional images. Stereological approaches were used to quantify volumes of stromal constituents. Three-dimensional imaging identified stromal extracellular vesicles, which constituted 3.9% of the villous stromal volume. These stromal extracellular vesicles were ovoid in shape, had a median length of 2750 nm (range 350-7730 nm) and TEM imaging confirmed that they were bounded by a lipid bilayer. Fifty-nine per cent of extracellular vesicles were in contact with a fibroblast-like stellate cell and these vesicles were significantly larger than those where no contact was observed. These stellate cells formed local networks with adherent junctions observed at contact points. This study demonstrates that the villous stroma contains extracellular macrovesicles which are considerably larger than any previously described in tissue or plasma. The size and abundance of these macrovesicles in the villous stroma highlight the diversity of extracellular vesicle biology and their roles within connective tissues.
| S-EPMC6904625 | biostudies-literature
Project description:Human placental villi are surfaced by a multinucleated and terminally differentiated epithelium, the syncytiotrophoblast, with a subjacent layer of mononucleated cytotrophoblasts that can divide and fuse to replenish the syncytiotrophoblast. The objectives of this study were i) to develop an approach to definitively identify and distinguish cytotrophoblasts from the syncytiotrophoblast, ii) to unambiguously determine the relative susceptibility of villous cytotrophoblasts and syncytiotrophoblast to constitutive and stress-induced apoptosis mediated by caspases, and iii) to understand the progression of apoptosis in villous trophoblasts. Confocal microscopy with co-staining for E-cadherin and DNA allowed us to clearly distinguish the syncytiotrophoblast from cytotrophoblasts and identified that many cytotrophoblasts are deeply interdigitated into the syncytiotrophoblast. Staining for specific markers of caspase-mediated apoptosis indicate that apoptosis occurs readily in cytotrophoblasts but is remarkably inhibited in the syncytiotrophoblast. To determine if an apoptotic cell or cell fragment was from a cytotrophoblast or syncytiotrophoblast, we found co-staining with E-cadherin along with a marker for apoptosis was essential: in the absence of E-cadherin staining, apoptotic cytotrophoblasts would easily be mistaken as representing localized regions of apoptosis in the syncytiotrophoblast. Regions with perivillous fibrin-containing fibrinoid contain the remnants of trophoblast apoptosis, and we propose this apoptosis occurs only after physical isolation of a region of the syncytium from the main body of the syncytium. We propose models for the progression of apoptosis in villous cytotrophoblasts and for why caspase-mediated apoptosis does not occur within the syncytium of placental villi.
| S-EPMC3631347 | biostudies-literature
Project description: Not available
| EMPIAR-11831 | biostudies-other
Project description:Recent advances in volume electron microscopy (vEM) allow unprecedented visualization of the electron-dense structures of cells, tissues and model organisms at nanometric resolution in three dimensions (3D). Light-based microscopy has been widely used for specific localization of proteins; however, it is restricted by the diffraction limit of light, and lacks the ability to identify underlying structures. Here, we describe a protocol for ultrastructural detection, in three dimensions, of a protein (Connexin 43) expressed in the intercalated disc region of adult murine heart. Our protocol does not rest on the expression of genetically encoded proteins and it overcomes hurdles related to pre-embedding and immunolabeling, such as the penetration of the label and the preservation of the tissue. The pre-embedding volumetric immuno-electron microscopy (pre-embedding vIEM) protocol presented here combines several practical strategies to balance sample fixation with antigen and ultrastructural preservation, and penetration of labeling with blocking of non-specific antigen binding sites. The small 1.4 nm gold along with surrounded silver used as a detection marker buried in the sample also serves as a functional conductive resin that significantly reduces the charging of samples. Our protocol also presents strategies for facilitating the successful cutting of the samples during serial block-face scanning electron microscopy (SBF-SEM) imaging. Our results suggest that the small gold-based pre-embedding vIEM is an ideal labeling method for molecular localization throughout the depth of the sample at subcellular compartments and membrane microdomains.
| S-EPMC10612668 | biostudies-literature
Project description:Background & objectivesDuring 6 to 8 wk of gestation, human placental villi show a complex pattern of morphogenesis. There is however, no large scale gene expression study exploring the temporal pattern of the developmental molecular networks in placental villi during the early weeks of gestation. We evaluated the transcriptome profiling of humn placental villus samples obtained from fertile women with voluntarily terminated normal pregnancies between 6-8 wk of gestation.MethodsTranscriptomic profiles of individual human placental villous samples from 25 women with normal pregnancies during 6 to 8 wk of gestation were examined using human whole genome expression arrays. Quantitative RT-PCR validation of copy numbers of transcripts for selected 15 genes and exploratory analysis of the microarray data revealed a high degree of quality assurance supportive of further clustering and differential analyses. Immunoblot and immunohistochemical analysis of selected five candidate proteins (CAGE1, CD9, SLC6A2, TANK and VEGFC) based on transcript profiles were done to assess the pattern of down stream informational flow.ResultsA large number (~9K) of genes with known functions were expressed in the experimental samples. The clustering analysis identified three major expression clusters with gestational age, and four co-expressional clusters. Differential analysis identified a highly discrete regulatory process involving only about 160 genes. Immunochemical analysis of selected candidate proteins based on transcript profiles revealed generally synchronous expression in human early placental villi.Interpretation & conclusionsSeveral signaling pathways linked to immunity (COL1, JAK2, JAK3, IL12, IL13, IL15, IL27, STAT3 and STAT5) were downregulated, while genes of the enriched category of antiviral immunity (ATF/AP1, IL10R and OAS) were clearly over-expressed. Transcriptional integration supportive of programmed development was observed in first trimester placental villi and it included regulation of apoptosis and cell cycle progression (ARRB1, ATR, BLM, CHRNA7, CHRNB1, FYN, KPNA4, and MTOR/FRAP), autophagy (ATG4B, ATG14, BAD, and BCL2), cell adhesion (CD9 and FN1) and epithelial-to-mesenchymal transition (CALD1, FN1, HEY1, MMP2, and WNT3A).
| S-EPMC3994729 | biostudies-literature
Project description:Total RNAs extracted from placental villi collected from women with (vaginal delivery) or without labor (cesarean section) at term (37-42 weeks of gestation) were hybridized to ClariomD microarrays and analyzed at the gene level to evaluate differential expression genes postlabor
2022-10-30 | E-MTAB-12012 | biostudies-arrayexpress
Project description:The placenta is the organ that mediates transport of nutrients and waste materials between mother and fetus. Synchrotron X-ray fluorescence (SXRF) microanalysis is a tool for imaging the distribution and quantity of elements in biological tissue, which can be used to study metal transport across biological membranes. Our aims were to pilot placental biopsy specimen preparation techniques that could be integrated into an ongoing epidemiology birth cohort study without harming rates of sample acquisition. We studied the effects of fixative (formalin or glutaraldehyde) and storage duration (30 days or immediate processing) on metal distribution and abundance and investigated a thaw-fixation protocol for archived specimens stored at -80 °C. We measured fixative elemental composition with and without a placental biopsy via inductively coupled plasma mass spectrometry (ICP-MS) to quantify fixative-induced elemental changes. Formalin-fixed specimens showed hemolysis of erythrocytes. The glutaraldehyde-paraformaldehyde solution in HEPES buffer (GTA-HEPES) had superior anatomical preservation, avoided hemolysis, and minimized elemental loss, although some cross-linking of exogenous Zn was evident. Elemental loss from tissue stored in fixative for 1 month showed variable losses (?40 % with GTA-HEPES), suggesting storage duration be controlled for. Thawing of tissue held at -80 °C in a GTA-HEPES solution provided high-quality visual images and elemental images.
| S-EPMC4663034 | biostudies-literature