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Published on: February 7, 2012
Evidence for medial/lateral specification and positional information within the presomitic mesoderm
C Freitas1, S Rodrigues, J B Charrier
1Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, 2780-156 Oeiras, Portugal.
Development (Cambridge, England)
|December 19, 2001
Summary
Vertebrate segmentation relies on a molecular clock within presomitic cells. This clock provides positional information along the medial/lateral axis, with medial cells driving somite formation.
Area of Science:
- Developmental Biology
- Molecular Biology
- Embryogenesis
Background:
- Somitogenesis, the formation of somites, is a key process in vertebrate embryonic development.
- A molecular clock, involving cyclic gene expression every 90 minutes, regulates somitogenesis in avian embryos.
- The presomitic mesoderm is the source of cells that form somites.
Purpose of the Study:
- To investigate the spatial and temporal dynamics of the molecular clock in the presomitic mesoderm.
- To determine if the molecular clock provides positional information along the medial/lateral axis.
- To understand the role of different regions of the presomitic mesoderm in somite formation.
Main Methods:
- Analysis of dynamic gene expression patterns in the prospective presomitic territory.
- Correlation of expression patterns with quail/chick fate-mapping.
- In vitro culture of medial and lateral presomitic cells.
Main Results:
- A 'wave' of cyclic gene expression travels along the medial/lateral axis of the presomitic mesoderm.
- Medial and lateral presomitic mesoderm exhibit asynchronous gene expression.
- Medial presomitic cells can form somites independently, while lateral cells cannot.
Conclusions:
- The molecular clock in somitogenesis provides positional information along both anterior/posterior and medial/lateral axes.
- Morphological and molecular segmentation information is segregated within the medial/lateral presomitic axis.
- Medial presomitic cells are essential for initiating somite formation and segmentation.
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