Size-reduced embryos reveal a gradient scaling-based mechanism for zebrafish somite formation

Kana Ishimatsu* (Corresponding Author), Tom W. Hiscock, Zach M. Collins, Dini Wahyu Kartika Sari, Kenny Lischer, David L. Richmond, Yasumasa Bessho, Takaaki Matsui, Sean G. Megason

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)


Little is known about how the sizes of animal tissues are controlled. A prominent example is somite size, which varies widely both within an individual and across species. Despite intense study of the segmentation clock governing the timing of somite generation, how it relates to somite size is poorly understood. Here, we examine somite scaling and find that somite size at specification scales with the length of the presomitic mesoderm (PSM) despite considerable variation in PSM length across developmental stages and in surgically size-reduced embryos. Measurement of clock period, axis elongation speed and clock gene expression patterns demonstrate that existing models fail to explain scaling. We posit a 'clock and scaled gradient' model, in which somite boundaries are set by a dynamically scaling signaling gradient across the PSM. Our model not only explains existing data, but also makes a unique prediction that we confirm experimentally - the formation of periodic 'echoes' in somite size following perturbation of the size of one somite. Our findings demonstrate that gradient scaling plays a central role in both progression and size control of somitogenesis.

Original languageEnglish
Article numberdev161257
Number of pages13
JournalDevelopment (Cambridge, England)
Issue number11
Early online date11 Jun 2018
Publication statusPublished - Jun 2018

Bibliographical note

Acknowledgements: We thank O. Pourquié, A. Aulehla and A. Oates for critical discussion. Some images were taken at the Nikon Imaging Center at Harvard Medical School

Funding: The work was supported by the PRESTO program of the Japan Science and Technology Agency and a National Institutes of Health grant (R01GM107733). This work was partially supported by Grants-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan(Y.B. and T.M.). T.W.H. was supported by a Herchel Smith Graduate Fellowship(University of Cambridge). K.I. acknowledges a Postdoctoral Fellowship for Research Abroad (Japan Society for the Promotion of Science).

Deposited in PMC for release after 12 months


  • Fgf gradient
  • Mathematical modeling
  • PSM
  • Quantitative imaging
  • Scaling
  • Segmentation clock
  • Somite
  • Zebrafish


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