A flattened mouse embryo: Leveling the playing field

Behringer, Richard R.; Wakamiya, Maki; Tsang, Tania E.; Tam, Patrick

doi:10.1002/1526-968x(200009)28:1<23::aid-gene30>3.0.co;2-g

Cited by 42 publications

(24 citation statements)

References 26 publications

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“…The human epiblast is a disk-shaped epithelium at gastrulation and the cup-like mouse embryo is often approximated as a disk 32,33 . The number of cells in mammalian embryos at this stage is comparable to our larger disks.…”

Section: Discussionmentioning

confidence: 99%

A method to recapitulate early embryonic spatial patterning in human embryonic stem cells

et al. 2014

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Embryos allocate cells to the three germ layers in a spatially ordered sequence. Human embryonic stem cells (hESCs) can generate the three germ layers in culture, however, differentiation is typically heterogeneous and spatially disordered. Here we show that geometric confinement is sufficient to trigger self-organized patterning in hESCs. In response to BMP4, these colonies reproducibly differentiate to an outer trophectoderm-like ring, an inner ectodermal circle and a ring of mesendoderm expressing primitive-streak markers in between. Fates are defined relative to the boundary with a fixed length scale: small colonies correspond to the outer layers of larger ones. Inhibitory signals limit the range of BMP4 signaling to the colony edge and induce a gradient of Activin/Nodal signaling that patterns mesendodermal fates. These results demonstrate that the intrinsic tendency of stem cells to make patterns can be harnessed by controlling colony geometries, and provide a quantitative assay for studying paracrine signaling.

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Section: Discussionmentioning

confidence: 99%

A method to recapitulate early embryonic spatial patterning in human embryonic stem cells

et al. 2014

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“…2). In order to relate the two distinct configurations, Behringer et al [55] proposed a flattened model of the mouse embryo. While the hypoblast underneath the epiblast in the embryonic disc may be equivalent to VE in mice, the extra-embryonic trophoblast and yolk sac epithelium immediately surrounding the periphery of the embryonic disc can be regarded as rodent ExE and extra-embryonic VE, respectively.…”

Section: Germ Cell Lineage Specification In Vivomentioning

confidence: 99%

Germ cell specification and pluripotency in mammals: a perspective from early embryogenesis

Irie

Tang

Surani

2014

Reprod Medicine & Biology

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Germ cells are unique cell types that generate a totipotent zygote upon fertilization, giving rise to the next generation in mammals and many other multicellular organisms. How germ cells acquire this ability has been of considerable interest. In mammals, primordial germ cells (PGCs), the precursors of sperm and oocytes, are specified around the time of gastrulation. PGCs are induced by signals from the surrounding extra-embryonic tissues to the equipotent epiblast cells that give rise to all cell types. Currently, the mechanism of PGC specification in mammals is best understood from studies in mice. Following implantation, the epiblast cells develop as an egg cylinder while the extra-embryonic ectoderm cells which are the source of important signals for PGC specification are located over the egg cylinder. However, in most cases, including humans, the epiblast cells develop as a planar disc, which alters the organization and the source of the signaling for cell fates. This, in turn, might have an effect on the precise mechanism of PGC specification in vivo as well as in vitro using pluripotent embryonic stem cells. Here, we discuss how the key early embryonic differences between rodents and other mammals may affect the establishment of the pluripotency network in vivo and in vitro, and consequently the basis for PGC specification, particularly from pluripotent embryonic stem cells in vitro.

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“…In modern triploblastic metazoans, EMT is used as a mechanism for reorganizing groups of progenitor cells into a more complex set of juxtaposed tissues, thereby allowing new inductive interactions (e.g. Behringer et al, 2000;Tam et al, 2001). For this reason it is important that EMTs occur in the correct place, at the right time and in the right sequence, such that progenitor cells come to lie in the appropriate pattern.…”

Section: Overviewmentioning

confidence: 99%

Mechanisms, mechanics and function of epithelial–mesenchymal transitions in early development

Shook

Keller

2003

Mechanisms of Development

508

428

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Epithelial-mesenchymal transitions (EMTs) are an important mechanism for reorganizing germ layers and tissues during embryonic development. They have both a morphogenic function in shaping the embryo and a patterning function in bringing about new juxtapositions of tissues, which allow further inductive patterning events to occur [Genesis 28 (2000) 23]. Whereas the mechanics of EMT in cultured cells is relatively well understood [reviewed in Biochem. Pharmacol. 60 (2000) 1091; Cell 105 (2001) 425; Bioessays 23 (2001) 912], surprisingly little is known about EMTs during embryonic development [reviewed in Acta Anat. 154 (1995) 8], and nowhere is the entire process well characterized within a single species. Embryonic (developmental) EMTs have properties that are not seen or are not obvious in culture systems or cancer cells. Developmental EMTs are part of a specific differentiative path and occur at a particular time and place. In some types of embryos, a relatively intact epithelium must be maintained while some of its cells de-epithelialize during EMT. In most cases de-epithelialization (loss of apical junctions) must occur in an orderly, patterned fashion in order that the proper morphogenesis results. Interestingly, we find that de-epithelialization is not always necessarily tightly coupled to the expression of mesenchymal phenotypes.Developmental EMTs are multi-step processes, though the interdependence and obligate order of the steps is not clear. The particulars of the process vary between tissues, species, and specific embryonic context. We will focus on 'primary' developmental EMTs, which are those occurring in the initial epiblast or embryonic epithelium. 'Secondary' developmental EMT events are those occurring in epithelial tissues that have reassembled within the embryo from mesenchymal cells. We will review and compare a number of primary EMT events from across the metazoans, and point out some of the many open questions that remain in this field.

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A flattened mouse embryo: Leveling the playing field

Cited by 42 publications

References 26 publications

A method to recapitulate early embryonic spatial patterning in human embryonic stem cells

A method to recapitulate early embryonic spatial patterning in human embryonic stem cells

Germ cell specification and pluripotency in mammals: a perspective from early embryogenesis

Mechanisms, mechanics and function of epithelial–mesenchymal transitions in early development

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