Independent assignment of antero-posterior and dorso-ventral positional values in the developing chick hindbrain

Simon, Horst H.; Hornbruch, Amata; Lumsden, Andrew

doi:10.1016/s0960-9822(95)00041-8

Cited by 97 publications

(38 citation statements)

References 42 publications

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“…Indeed, all artificial rhombomere pair combinations behave in strict accordance to a "anterior odd" code that either exists normally or can be produced by grafting. Thus, early AP positional value (Guthrie and Lumsden, 1992;Simon et al, 1995;Grapin-Botton et al, 1998;Dupé and Lumsden, 2001) has no obvious influence on the future pattern of rhythmic activities. The processes leading to episodes certainly begin after HH10 and probably cease with the downregulation of Krox20 expression in r3 at HH15-HH20 (Wilkinson et al, 1989;Schneider-Maunoury et al, 1993.…”

Section: Discussionmentioning

confidence: 99%

“…Local changes in anteroposterior Hox patterns (Brunet and Ghysen, 1999;Dominguez del Toro et al, 2001) as well as in the interaction of Hox genes with dorsoventral establishment of neuronal diversity (Simon et al, 1995;Gaufo et al, 2003;Pattyn et al, 2003) may offer novel opportunities for the evolution of distinct subsets of neurons and the emergence of novel functions. We have now identified a robust developmental specification mechanism that is instructive for the maturation of the activity pattern of hindbrain neuronal circuits.…”

Section: Development Of the Parafacial Rhythm Generator May Be Consermentioning

confidence: 99%

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Induction of a Parafacial Rhythm Generator by Rhombomere 3 in the Chick Embryo

Coutinho¹,

Borday²,

Gilthorpe³

et al. 2004

J. Neurosci.

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Observations of knock-out mice suggest that breathing at birth requires correct development of a specific hindbrain territory corresponding to rhombomeres (r) 3 and 4. Focusing on this territory, we examined the development of a neuronal rhythm generator in the chick embryo. We show that rhythmic activity in r4 is inducible after developmental stage 10 through interaction with r3. Although the nature of this interaction remains obscure, we find that the expression of Krox20, a segmentation gene responsible for specifying r3 and r5, is sufficient to endow other rhombomeres with the capacity to induce rhythmic activity in r4. Induction is robust, because it can be reproduced with r2 and r6 instead of r4 and with any hindbrain territory that normally expresses Krox20 (r3, r5) or can be forced to do so (r1, r4). Interestingly, the interaction between r4 and r3/r5 that results in rhythm production can only take place through the anterior border of r4, revealing a heretofore unsuspected polarity in individual rhombomeres. The r4 rhythm generator appears to be homologous to a murine respiratory parafacial neuronal system developing in r4 under the control of Krox20 and Hoxa1. These results identify a late role for Krox20 at the onset of neurogenesis.

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Section: Discussionmentioning

confidence: 99%

Section: Development Of the Parafacial Rhythm Generator May Be Consermentioning

confidence: 99%

Induction of a Parafacial Rhythm Generator by Rhombomere 3 in the Chick Embryo

Coutinho¹,

Borday²,

Gilthorpe³

et al. 2004

J. Neurosci.

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“…a coarse rostrocaudal pattern is established even earlier, at neural plate stages, providing a substrate upon which later dorsoventral patterning acts Simon et al, 1995). Rhombomeres express different combinations of Hox genes, which play roles in segmentation, rhombomere patterning and neuronal differentiation .…”

Section: Introductionmentioning

confidence: 99%

Somatic motoneurone specification in the hindbrain: the influence of somite-derived signals, retinoic acid and Hoxa3

2003

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We have investigated the mechanisms involved in generating hindbrain motoneurone subtypes, focusing on somatic motoneurones, which are confined to the caudal hindbrain within rhombomeres 5-8. Following heterotopic transplantation of rhombomeres along the rostrocaudal axis at various developmental stages, we have found that the capacity of rhombomeres to generate somatic motoneurones is labile at the neural plate stage but becomes fixed just after neural tube closure, at stage 10-11. Grafting of somites or retinoic acid-loaded beads beneath the rostral hindbrain induced the formation of somatic motoneurones in rhombomere 4 only, and Hox genes normally expressed more caudally (Hoxa3, Hoxd4) were induced in this region. Targeted overexpression of Hoxa3 in the rostral hindbrain led to the generation of ectopic somatic motoneurones in ventral rhombomeres 1-4, and was accompanied by the repression of the dorsoventral patterning gene Irx3. Taken together, these observations suggest that the somites,retinoic acid and Hox genes play a role in patterning somatic motoneurones in vivo.

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“…A variety of evidence indicates that AP regionalization can generate transverse blocks of neuroepithelium which have distinct competence to respond to the same inductive signal (Ericson et al, 1995;Hynes et al, 1995b;Simon et al, 1995;Shimamura and Rubenstein, 1997). This phenomenon is clearly illustrated by inductive responses to Shh.…”

Section: Antero-posterior (Ap) Patterningmentioning

confidence: 99%

“…Because expression is not detected in the neural plate, the lack of forebrain and midbrain in Lim1 mutants is evidence for an essential role of this mesoderm in anterior CNS development (Shawlot and Behringer, 1995). Understanding the mechanisms underlying the Otx2 phenotype is more difficult because of the dynamics of its expression pattern and the complexity of its molecular interactions.A variety of evidence indicates that AP regionalization can generate transverse blocks of neuroepithelium which have distinct competence to respond to the same inductive signal (Ericson et al, 1995;Hynes et al, 1995b;Simon et al, 1995;Shimamura and Rubenstein, 1997). This phenomenon is clearly illustrated by inductive responses to Shh.…”

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confidence: 99%

Molecular mechanisms controlling brain development: an overview of neuroepithelial secondary organizers

Vieira¹,

Pombero²,

et al. 2010

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. In this review, we will describe the principle aspects of CNS development in birds and mammals, starting from early stages of embryogenesis (gastrulation and neurulation) and culminating with the formation of a variety of different regions which contribute to the structural complexity of the brain (regionalization and morphogenesis). We will pay special attention to the cellular and molecular mechanisms involved in neural tube regionalization and the key role played by localized secondary organizers in the patterning of neural primordia. KEY WORDS: patterning, neural plate, neural tube, gastrulation, neurulation, secondary organizer, anterior neural ridge, zona limitans intrathalamica, isthmic organizer Neural plate and neural tube formationA fundamental early step in neural development is the allocation of a group of ectodermal cells as precursors of the entire nervous system (Hemmati-Brivanlou and Melton, 1997). This process involves an inductive interaction first demonstrated in amphibian embryos by Spemann and Mangold in the 1920's (see Spemann and Mangold, 2001). Their experiments which involved the grafting of differently pigmented species of newt established the concept of neural induction as an instructive interaction between the dorsal lip of the blastopore (the "organizer") and the neighboring ectoderm. The discovery of a neural organization center for the amphibian gastrula initiated a search for homologous structures in other vertebrates. Soon thereafter, the equivalent region was discovered in most vertebrate species, including the shield of teleosts. In birds and mammals, the region was named "Hensen's node" and "the node", respectively. When C.H. Waddington transplanted the Hensen node of a chick embryo, he observed the induction of Int. J. Dev. Biol. 54: 7-20 (2010) Abbreviations used in this paper: ANR, anterior neural ridge; AP, anteroposterior; BMP, bone morphogenetic protein; DV, dorso-ventral; FGF, fibroblast growth factor; IsO, Isthmic organizer; ML, medio-lateral; TGF, transforming growth factor; ZLI, zona limitans intrathalamica.an ectopic neural plate or the formation of a partial new embryonic axis containing neural tube, notochord and somites (Waddington, 1933;Waddington, 1936). This demonstration provided the first evidence that in chick embryos, the nervous system is induced by signals from non-neural cells. Recent works demonstrated that the capacity of ectodermal cells to undergo neural differentiation represents their default state. In fact, neural differentiation must be suppressed in the lateral ectoderm by signals transmitted between neighboring cells, in order to develop as epidermis. These molecular signals are members of the bone morphogenetic protein (BMP) subclass of transforming growth factor β (TGF-β)-related proteins (for review see Wittler and Kessel, 2004). C. Vieira et al.Recent studies using chick embryos have shown that neural induction really begins prior to the formation of the organizer region and thus must be initiated by signals derived from other cellul...

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Independent assignment of antero-posterior and dorso-ventral positional values in the developing chick hindbrain

Cited by 97 publications

References 42 publications

Induction of a Parafacial Rhythm Generator by Rhombomere 3 in the Chick Embryo

Induction of a Parafacial Rhythm Generator by Rhombomere 3 in the Chick Embryo

Somatic motoneurone specification in the hindbrain: the influence of somite-derived signals, retinoic acid and Hoxa3

Molecular mechanisms controlling brain development: an overview of neuroepithelial secondary organizers

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