Talk:Yolk Sac Development
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Cite this page: Hill, M.A. (2020, July 4) Embryology Yolk Sac Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Yolk_Sac_Development
10 Most Recent Papers
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Yolk Sac Development
<pubmed limit=5>Yolk Sac Development</pubmed>
<pubmed limit=5>Meckel's Diverticulum</pubmed>
The phenotypic and functional properties of mouse yolk-sac-derived embryonic macrophages
Dev Biol. 2018 Oct 1;442(1):138-154. doi: 10.1016/j.ydbio.2018.07.009. Epub 2018 Jul 30.
Yosef N1, Vadakkan TJ1, Park JH2, Poché RA1, Thomas JL3, Dickinson ME4.
Abstract Macrophages are well characterized as immune cells. However, in recent years, a multitude of non-immune functions have emerged many of which play essential roles in a variety of developmental processes (Wynn et al., 2013; DeFalco et al., 2014). In adult animals, macrophages are derived from circulating monocytes originating in the bone marrow, but much of the tissue-resident population arise from erythro-myeloid progenitors (EMPs) in the extra-embryonic yolk sac, appearing around the same time as primitive erythroblasts (Schulz et al., 2012; Kierdorf et al., 2013; McGrath et al., 2015; Gomez Perdiguero et al., 2015; Mass et al., 2016). Of particular interest to our group, macrophages have been shown to act as pro-angiogenic regulators during development (Wynn et al., 2013; DeFalco et al., 2014; Hsu et al., 2015), but there is still much to learn about these early cells. The goal of the present study was to isolate and expand progenitors of yolk-sac-derived Embryonic Macrophages (EMs) in vitro to generate a new platform for mechanistic studies of EM differentiation. To accomplish this goal, we isolated pure (>98%) EGFP+ populations by flow cytometry from embryonic day 9.5 (E9.5) Csf1r-EGFP+/tg mice, then evaluated the angiogenic potential of EMs relative to Bone Marrow-Derived Macrophages (BMDMs). We found that EMs expressed more pro-angiogenic and less pro-inflammatory macrophage markers than BMDMs. EMs also promoted more endothelial cell (EC) cord formation in vitro, as compared to BMDMs in a manner that required direct cell-to-cell contact. Importantly, EMs preferentially matured into microglia when co-cultured with mouse Neural Stem/Progenitor Cells (NSPCs). In conclusion, we have established a protocol to isolate and propagate EMs in vitro, have further defined specialized properties of yolk-sac-derived macrophages, and have identified EM-EC and EM-NSPC interactions as key inducers of EC tube formation and microglial cell maturation, respectively. KEYWORDS: Angiogenesis; Endothelial Cells; Macrophages; Microglia; Neural Stem/Progenitor Cells; Yolk sac PMID: 30016639 PMCID: PMC6190604 [Available on 2019-10-01] DOI: 10.1016/j.ydbio.2018.07.009
Expression of thyroid hormone regulator genes in the yolk sac membrane of the developing chicken embryo
J Reprod Dev. 2017 Oct 18;63(5):463-472. doi: 10.1262/jrd.2017-017. Epub 2017 Jun 25.
Too HC1,2, Shibata M1, Yayota M3, Darras VM4, Iwasawa A3.
Abstract Thyroid hormones (THs) are essential for the correct development of nearly every structure in the body from the very early stages of development, yet the embryonic thyroid gland is not functional at these stages. To clarify the roles of the egg yolk as a source of THs, the TH content in the yolk and the expression of TH regulator genes in the yolk sac membrane were evaluated throughout the 21-day incubation period of chicken embryos. The yolk TH content (22.3 ng triiodothyronine and 654.7 ng thyroxine per total yolk on day 4 of incubation) decreased almost linearly along with development. Real-time PCR revealed gene expression of transthyretin, a principal TH distributor in the chicken, and of a TH-inactivating iodothyronine deiodinase (DIO3), until the second week of incubation when the embryonic pituitary-thyroid axis is generally thought to start functioning. The TH-activating deiodinase (DIO2) and transmembrane transporter of thyroxine (SLCO1C1) genes were expressed in the last week of incubation, which coincided with a marked increase of circulating thyroxine and a reduction in the yolk sac weight. DIO1, which can remove iodine from inactive THs, was expressed throughout the incubation period. It is assumed that the chicken yolk sac inactivates THs contained abundantly in the yolk and supplies the hormones to the developing embryo in appropriate concentrations until the second week of incubation, while THs may be activated in the yolk sac membrane in the last week of incubation. Additionally, the yolk sac could serve as a source of iodine for the embryo. KEYWORDS: Chicken; Iodothyronine deiodinase; Real-time PCR; Thyroid hormones; Yolk sac PMID: 28652559 PMCID: PMC5649095 DOI: 10.1262/jrd.2017-017
Am J Obstet Gynecol. 2016 Feb;214(2):192-202. doi: 10.1016/j.ajog.2015.09.082. Epub 2015 Sep 30.
Dong D1, Reece EA2, Lin X1, Wu Y1, AriasVillela N1, Yang P3. Author information Abstract Maternal diabetes mellitus is a significant risk factor for structural birth defects, including congenital heart defects and neural tube defects. With the rising prevalence of type 2 diabetes mellitus and obesity in women of childbearing age, diabetes mellitus-induced birth defects have become an increasingly significant public health problem. Maternal diabetes mellitus in vivo and high glucose in vitro induce yolk sac injuries by damaging the morphologic condition of cells and altering the dynamics of organelles. The yolk sac vascular system is the first system to develop during embryogenesis; therefore, it is the most sensitive to hyperglycemia. The consequences of yolk sac injuries include impairment of nutrient transportation because of vasculopathy. Although the functional relationship between yolk sac vasculopathy and structural birth defects has not yet been established, a recent study reveals that the quality of yolk sac vasculature is related inversely to embryonic malformation rates. Studies in animal models have uncovered key molecular intermediates of diabetic yolk sac vasculopathy, which include hypoxia-inducible factor-1α, apoptosis signal-regulating kinase 1, and its inhibitor thioredoxin-1, c-Jun-N-terminal kinases, nitric oxide, and nitric oxide synthase. Yolk sac vasculopathy is also associated with abnormalities in arachidonic acid and myo-inositol. Dietary supplementation with fatty acids that restore lipid levels in the yolk sac lead to a reduction in diabetes mellitus-induced malformations. Although the role of the human yolk in embryogenesis is less extensive than in rodents, nevertheless, human embryonic vasculogenesis is affected negatively by maternal diabetes mellitus. Mechanistic studies have identified potential therapeutic targets for future intervention against yolk sac vasculopathy, birth defects, and other complications associated with diabetic pregnancies. KEYWORDS: embryopathy; maternal diabetes mellitus; vasculopathy; yolk sac PMID: 26432466 PMCID: PMC4744545 DOI: 10.1016/j.ajog.2015.09.082
Definitive Hematopoiesis in the Yolk Sac Emerges from Wnt-Responsive Hemogenic Endothelium Independently of Circulation and Arterial Identity
Stem Cells. 2016 Feb;34(2):431-44. doi: 10.1002/stem.2213. Epub 2015 Oct 23.
Frame JM1,2, Fegan KH1, Conway SJ3, McGrath KE1, Palis J1.
Abstract Adult-repopulating hematopoietic stem cells (HSCs) emerge in low numbers in the midgestation mouse embryo from a subset of arterial endothelium, through an endothelial-to-hematopoietic transition. HSC-producing arterial hemogenic endothelium relies on the establishment of embryonic blood flow and arterial identity, and requires β-catenin signaling. Specified prior to and during the formation of these initial HSCs are thousands of yolk sac-derived erythro-myeloid progenitors (EMPs). EMPs ensure embryonic survival prior to the establishment of a permanent hematopoietic system, and provide subsets of long-lived tissue macrophages. While an endothelial origin for these HSC-independent definitive progenitors is also accepted, the spatial location and temporal output of yolk sac hemogenic endothelium over developmental time remain undefined. We performed a spatiotemporal analysis of EMP emergence, and document the morphological steps of the endothelial-to-hematopoietic transition. Emergence of rounded EMPs from polygonal clusters of Kit(+) cells initiates prior to the establishment of arborized arterial and venous vasculature in the yolk sac. Interestingly, Kit(+) polygonal clusters are detected in both arterial and venous vessels after remodeling. To determine whether there are similar mechanisms regulating the specification of EMPs with other angiogenic signals regulating adult-repopulating HSCs, we investigated the role of embryonic blood flow and Wnt/β-catenin signaling during EMP emergence. In embryos lacking a functional circulation, rounded Kit(+) EMPs still fully emerge from unremodeled yolk sac vasculature. In contrast, canonical Wnt signaling appears to be a common mechanism regulating hematopoietic emergence from hemogenic endothelium. These data illustrate the heterogeneity in hematopoietic output and spatiotemporal regulation of primary embryonic hemogenic endothelium. KEYWORDS: Embryo; Endothelial cell; Hemangioblast; Hematopoiesis; Hematopoietic progenitors; Hematopoietic stem cells; Vascular development PMID: 26418893 PMCID: PMC4755868 DOI: 10.1002/stem.2213