Yolk-sac hematopoiesis

Palis, James; Yöder, Mervin C.

doi:10.1016/s0301-472x(01)00669-5

Cited by 386 publications

(308 citation statements)

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“…3K, 4F, F 0 ). During early organogenesis, the survival and development of the embryo is critically dependent on the formation and maintenance of a functional yolk sac circulation (Palis and Yoder, 2001). In Ric-8 À/À embryos, the amalgamation of blood islands was aberrant and yolk sac vasculature was malformed at E8.5, whereas in the wild type embryos the blood islands with hematocytoblasts were present in the visceral yolk sac (Fig.…”

Section: Ric-8 2/2 Embryos Are Not Competent In Organogenesismentioning

confidence: 99%

Nucleotide exchange factor RIC‐8 is indispensable in mammalian early development

Tõnissoo¹,

Lulla²,

Meier³

et al. 2010

Developmental Dynamics

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The guanine nucleotide exchange factor RIC-8 is a conserved protein essential for the asymmetric division in the early embryogenesis in different organisms. The function of RIC-8 in mammalian development is not characterized so far. In this study we map the expression of RIC-8 during the early development of mouse. To elucidate the RIC-8 function we used Ric-8 2/2 mutant embryos. The Ric-8 2/2 embryos reach the gastrulation stage but do not develop further and die at E6.5-E8.5. We characterized the Ric-8 2/2 embryonic phenotype by morphological and marker gene analyses. The gastrulation is initiated in Ric-8 2/2 embryos but their growth is retarded, epiblast and mesoderm disorganized. Additionally, the basement membrane is defective, amnion folding and the formation of allantois are interfered, also the cavitation. Furthermore, the orientation of the Ric-8 2/2 embryo in the uterus was abnormal. Our study reveals that the activity of RIC-8 protein is irreplaceable for the correct gastrulation of mouse embryo. Developmental Dynamics 239:3404-3415,

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Section: Ric-8 2/2 Embryos Are Not Competent In Organogenesismentioning

confidence: 99%

Nucleotide exchange factor RIC‐8 is indispensable in mammalian early development

Tõnissoo¹,

Lulla²,

Meier³

et al. 2010

Developmental Dynamics

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“…It has been well-documented that extraembryonic tissues, including the yolk sac and allantois in birds and mammals and the placenta in mammals, contribute to the generation of definitive erythrocytes during amniote development (Dantschakoff, 1908;Moore and Owen, 1965;Moore and Metcalf, 1970;Dieterlen-Lievre et al, 1976;Weissman et al, 1978;Beaupain et al, 1979;Caprioli et al, 1998;Palis and Yoder, 2001;McGrath and Palis, 2005;Mikkola et al, 2005;Ottersbach and Dzierzak, 2005;Zeigler et al, 2006;Corbel et al, 2007;Samokhvalov et al, 2007;Lux et al, 2008;Rhodes et al, 2008). What remain not well-understood are the precise cellular source and niche of definitive erythropoiesis and the relative contributions of intraembryonic-and extraembryonic-generated definitive erythrocytes in embryonic blood.…”

Section: Introductionmentioning

confidence: 99%

Definitive erythropoiesis in chicken yolk sac

Nagai¹,

Sheng²

2008

Developmental Dynamics

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The first wave of erythropoiesis in amniotic animals generates all primitive erythrocytes and takes place exclusively in yolk sac mesoderm. It is less clear, however, to what extend and for how long the yolk sac contributes to the second wave of erythropoiesis which gives rise to definitive erythrocytes for later embryonic and adult use. Here, we examine the initiation, duration, and site of definitive erythrocyte formation in chicken yolk sac. We show that the earliest definitive erythrocytes are generated in yolk sac venous vessels surrounding major arteries at embryonic day (E) 4 -4.5, and that mature definitive erythrocytes enter circulating at E4.5-E5. This takes place at a time when yolk sac vasculature remodels extensively to generate paired arterial/venous vessels. The yolk sac remains the predominant site for definitive erythropoiesis from E5 to E10, and continues to generate definitive erythrocytes at least until E15. Similar to primitive erythropoiesis, definitive erythropoiesis in the yolk sac is accompanied by the expression of transcriptional regulators gata1, scl, and lmo2. Furthermore, our data suggest that one main source of definitive erythropoietic cells is the pre-existing vascular endothelial cells. It remains unclear whether yolk sac derived hematopoietic progenitors that do not undergo erythropoiesis in the yolk sac may take up intraembryonic niches and contribute to erythropoietic stem cell population after hatching.

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“…PKC activation depends on the phosphatidylinositol (PI)-3, 4, 5-triphosphate (PIP 3 ), which is mainly induced by PI-3 kinase. 3Ј-PI-dependent protein kinase 1, which binds with high affinity to PIP, 3 phosphorylates and activates PKC . 3 Leseux et al show that the role of PKC in the inhibition of Raf-1 signaling does not involve Raf-1 kinase inhibitor protein (RKIP).…”

Section: The Rituximab-pkc /Raf-1/mtor Connection -------------------mentioning

confidence: 99%

“…3Ј-PI-dependent protein kinase 1, which binds with high affinity to PIP, 3 phosphorylates and activates PKC . 3 Leseux et al show that the role of PKC in the inhibition of Raf-1 signaling does not involve Raf-1 kinase inhibitor protein (RKIP). They find that, unlike in Burkitt lymphoma, 2 …”

Section: The Rituximab-pkc /Raf-1/mtor Connection -------------------mentioning

confidence: 99%

“…1,2 In contrast, in mammals, primitive hematopoiesis originates from mesoderm outside the embryo that migrates onto the embryonic yolk sac to develop blood islands; during the course of further development, it migrates to the aorta-gonadmesonephros (AGM) region, fetal liver, and finally the bone marrow for "definitive" hematopoiesis. [1][2][3] Macrophages have been identified as the first leukocytes to be derived during developmental myelopoiesis in vertebrate embryos, originate from the RBI, before dispersing throughout the embryonic mesenchyme prior to blood circulation in the developing zebrafish. Neutrophilic granulocytes appear next in primitive hematopoiesis and are identified in blood circulation and connective tissue (mesenchyme) by 48 hours after fertilization (hpf).…”

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confidence: 99%

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