Control of segment number in vertebrate embryos

Nature. 2008 Jul 17;454(7202):335-9. doi: 10.1038/nature07020. Epub 2008 Jun 18.


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 somitogenesis; in all of them, somitogenesis is brought to an end through a process in which the presomitic mesoderm, having first increased in size, gradually shrinks until it is exhausted, terminating somite formation. In snake embryos, however, the segmentation clock rate is much faster relative to developmental rate than in other amniotes, leading to a greatly increased number of smaller-sized somites.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Body Patterning* / genetics
  • Chick Embryo / embryology*
  • Gene Expression Regulation, Developmental
  • Mice / embryology*
  • Molecular Sequence Data
  • Snakes / embryology*
  • Somites / embryology*
  • Time Factors
  • Zebrafish / embryology*

Associated data

  • GENBANK/EU196456
  • GENBANK/EU196457
  • GENBANK/EU196458
  • GENBANK/EU196459
  • GENBANK/EU196460
  • GENBANK/EU196461
  • GENBANK/EU196462
  • GENBANK/EU196463
  • GENBANK/EU196464
  • GENBANK/EU196465
  • GENBANK/EU196466
  • GENBANK/EU232010