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Current developments in human stem cell research and clinical translation
Published in Christine Hauskeller, Arne Manzeschke, Anja Pichl, The Matrix of Stem Cell Research, 2019
Stephanie Sontag, Martin Zenke
After the implantation of the blastocyst on days 7–9 the ICM develops into the epiblast (De Paepe et al., 2014). Epiblast stem cells are still pluripotent but as they have undergone more developmental stages they are referred to as primed pluripotent stem cells to distinguish them from naïve pluripotent stem cells of the pre-implantation ICM (Boroviak and Nichols, 2014). Epiblast stem cells lose their pluripotency when a thickened structure, called the primitive streak, is formed along the midline of the epiblast, which at this stage defines the body axes and orientations of the future embryo: cranial (head) versus caudal (feet), anterior (front) versus posterior (back), as well as left versus right end. During this process (known as gastrulation) the single-layered epiblast is reorganized into a three-layered gastrula forming the three germ layers: ectoderm (outer layer), mesoderm (middle layer), and endoderm (inner layer).
The Twentieth Century
Published in Arturo Castiglioni, A History of Medicine, 2019
Gastrulation had long been recognized as a significant step in the sequence of events associated with organization of the embryo. It was known that a large portion of the ectoderm (the outermost of the three primitive layers) of the blastula swept downward to the blastopore (the mouth of the primitive gut, or archenteron), where it invaginated to produce the mesoderm and roof of the archenteron. Attempts at tracing the subsequent fate of different regions of this presumptive mesoderm were at first confined to the production of an injury in a single region, until W. vogt mapped out the fate of the different surface areas of the amphibian gastrula (1929), by staining circumscribed regions with vital dyes and tracing their subsequent migrations.
Integrin Function in Early Vertebrate Development: Perspectives from Studies of Amphibian Embryos
Published in Yoshikazu Takada, Integrins: The Biological Problems, 2017
Embryogenesis is characterized by a highly orchestrated series of changes in adhesion that mediate the interactions of cells with one another and with the extracellular matrix (ECM). The cellular rearrangements of the gastrula, the migration of neural crest and primordial germ cells, and the formation of neural connections are but a few of the more spectacular examples of the precision with which embryonic cells and tissues use adhesive mechanisms to play out their morphogenetic programs. These events are likely to require the diverse functional activities of a large number of adhesion molecules with differing specificities and affinities. The integrins are an example of such a family of receptors thought to play important functional roles during development.
Stiffness estimation of transversely anisotropic materials using a novel indentation tester with a rectangular hole
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Atsutaka Tamura, Mika Saiki, Jun-ichi Hongu, Takeo Matsumoto
This work has a few limitations. First, this measurement technique may not be universally applicable. Since we considered the material stiffness of the Xenopus laevis gastrula at an early developmental stage, i.e. a very young embryo, we assumed that the Young’s modulus of its ground matrix ranged from 1 to 5 Pa. Thus, our approach may not be applied to biological materials with Young’s modulus E ≫ 5 Pa or anisotropy ratio ≫ 3, because the deformation pattern may be different; for instance, when a material with a much higher anisotropy ratio (Epr ≫ E) is uniaxially compressed, it will deform into a spindle body rather than retaining a concentric spherical form and may result in hAP < hML, which is contradictory to the results shown in Figure 8(a)–(c).
Different cellular mechanisms from low- and high-dose zinc oxide nanoparticles-induced heart tube malformation during embryogenesis
Published in Nanotoxicology, 2022
Mengwei Wang, Ping Zhang, Zeyu Li, Yu Yan, Xin Cheng, Guang Wang, Xuesong Yang
After identifying the physical and chemical features (Figure 1), we firstly studied the cell viability, autophagy and apoptosis in response to ZnO NPs stimulation in H9c2 cells since they provide the index of cell survival (viability), and regulate cell survival or/and death through eliminating cellular dysfunctional components (autophagy) or initiating programmed cell death (apoptosis), i.e. making the decision of cell “living” or “death” when confronted with the “external stimuli” (Figure 2,3, Supplementary Figure 2). The cellular responses appeared clearly in a dose-dependent manner, i.e. the autophagy-activated living cells in the majority at low-dose ZnO NPs and numerous apoptotic cells for body-level content at high-dose ZnO NPs. Our scientific question, therefore, was if the ZnO NPs time- and dose-dependent cell responses occurred in their impact on early cardiogenesis with different mechanisms? To address this question, we carried out similar experiments in gastrula and late-stage chicken/mouse embryos and found increased trends of embryonic survival rates, embryonic size along long axis, malformations of heart tubes (Degree of malformation of heart tube as hypertrophy, closure defect, and bifida), and especially the apoptosis of precardiac cells in heart tubes with the ZnO NPs concentration increasing (Figure 5, Supplementary Figure 6–8). This strongly implied that massive cell death such as apoptosis was principally responsible for the high-dose ZnO NPs-induced heart tube malformation.
Polystyrene nanoplastics exposure caused defective neural tube morphogenesis through caveolae-mediated endocytosis and faulty apoptosis
Published in Nanotoxicology, 2021
Jia-hui Nie, Yao Shen, Mohamed Roshdy, Xin Cheng, Guang Wang, Xuesong Yang
To study whether the aforementioned PS-NPs adversely impact fetal development during the early developmental stage, gastrulation and neurulation, we administered PS-NPs to Hamburger-Hamilton (HH) (Hamburger and Hamilton 1951; Hamburger and Hamilton 1992) stage 0 chick embryos, which were incubated in EC culture (for ex ovo culture of early-stage avian embryos). Compared to control embryos, the embryonic developmental stages were delayed after PS-NPs exposure at 24 h and 36 h (Figure 4(A–C)). We also observed more severe malformation in embryos exposed to PS-NPs after 36-h incubation (Figure 4(D)). The length of HH10 chick embryos in the 60-nm PS-NP-treated group was significantly reduced compared with the control group, but no effect was noted in the 900-nm PS-NP-treated group (Figure 4(E)). The fluorescent images of the chick embryos exposed to PS-NPs-GFP revealed increased accumulation in the developing neural tube, including cranial and trunk regions (GFP channel in Figure 4(F)). Whole embryo immunofluorescent staining against Pax7 (Eggenschwiler and Anderson 2000) showed that the neural tube defect (NTD) frequently occurred in PS-NP-treated gastrula chick embryos (Figure 4(F,G)). In the higher magnification of sections, we observe the distribution of PS-NPs in the neural tube (white arrowheads in Figure 4(F)). These data indicated that PS-NPs exposure restricts gastrula chick embryos and induces aberrant neurulation.