Control of segment number in vertebrate embryos

  title={Control of segment number in vertebrate embryos},
  author={C{\'e}line Gomez and Ertuğrul M {\"O}zbudak and Joshua P. Wunderlich and Diana P Baumann and Julian Lewis and Olivier Pourqui{\'e}},
The vertebrate body axis is subdivided into repeated segments, best exemplified by the vertebrae that derive from embryonic somites. The number of somites is precisely defined for any given species but varies widely from one species to another. To determine the mechanism controlling somite number, we have compared somitogenesis in zebrafish, chicken, mouse and corn snake embryos. Here we present evidence that in all of these species a similar ‘clock-and-wavefront’ mechanism operates to control… 

Segment Number and Axial Identity in a Segmentation Clock Period Mutant

Developmental control of segment numbers in vertebrates.

  • C. GomezO. Pourquié
  • Biology, Environmental Science
    Journal of experimental zoology. Part B, Molecular and developmental evolution
  • 2009
It is proposed that during development, dissociation of the Hox- and segmentation-clock-dependent vertebral patterning systems explains the enormous diversity of vertebral formulae observed in vertebrates.

The zebrafish presomitic mesoderm elongates through compression-extension

A compression-extension mechanism of tissue elongation that highlights the need to better understand the role of tissue intrinsic and extrinsic forces play in regulating morphogenesis is proposed.

The chick somitogenesis oscillator is arrested before all paraxial mesoderm is segmented into somites

The results show that the chick somitogenesis oscillator is arrested before all paraxial mesoderm is segmented into somites, and endogenous retinoic acid is probably also involved in the termination of the process of segmentation, and in tail growth in general.

Somitogenesis in Vertebrate Development

Gathering evidence suggests that somitogenesis is regulated by a molecular oscillator mechanism that, together with a morphogenic gradient, stipulates when and where somites form.

Turn It Down a Notch

The pathophysiological relevance of NICD-FBXW7 interaction, whose defects have been linked to leukemia and a variety of solid cancers, is described.

Patterning and mechanics of somite boundaries in zebrafish embryos.

Mechanical stretching can modify the axial morphology of early chick embryos

The results strengthen the idea that somitic mesoderm self-organizes, and show that it is phenotypically plastic under variations in the mechanical environment.

Hox genes control vertebrate body elongation by collinear Wnt repression

The data indicate that a subset of progressively more posterior Hox genes, which are collinearly activated in vertebral precursors, repress Wnt activity with increasing strength leads to a graded repression of the Brachyury/T transcription factor, reducing mesoderm ingression and slowing down the elongation process.



Somite number and vertebrate evolution.

This work argues that somitogenesis shows uncoupling or dissociation from the conserved positional field encoded by genes of the zootype, and therefore violates the 'developmental hourglass' model.

An experimental and morphological analysis of the tail bud mesenchyme of the chick embryo

It is suggested that cell death may be a contributory factor in preventing segmentation in the chick embryo and that in the normal embryo massive cell death overtakes the tail bud mesoderm before it can segment.

The control of somitogenesis in mouse embryos.

  • P. Tam
  • Biology
    Journal of embryology and experimental morphology
  • 1981
It is proposed that axis formation and Somitogenesis are related morphogenetic processes and that embryonic growth controls the kinetics of somitogenesis, namely by regulating the number of cells allocated to each somite and the rate of somite formation.

Setting the Tempo in Development: An Investigation of the Zebrafish Somite Clock Mechanism

It is deduced that although her7 continues to oscillate in the anterior half of the PSM, it governs the future somite segmentation behaviour of the cells only while they are in the posterior half, which strongly support the mathematical model of how the somite clock works.

Two distinct sources for a population of maturing axial progenitors

It is shown that a specific topological arrangement of domains persists from the streak to the tail bud, and includes an area (the node-streak border) in which ectoderm that expresses primitive streak markers overlies the prospective notochord in the chordoneural hinge.