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Accueil du site > Animations Scientifiques > Séminaires 2011 > Loïc Le Goff — The mechanics of a growing epithelium

Loïc Le Goff — The mechanics of a growing epithelium

Speaker :

Loïc Le Goff , IBDML - Institut de Biologie du Développement de Marseille-Luminy

When :

Wednesday 23 February at 11am

Where :

C023 (RDC LR6 côté Centre Blaise Pascal)

Title :

The mechanics of a growing epithelium

Abstract :

The size and shape of a growing tissue are partly imposed by the frequency and orientation of cell divisions. While the molecular pathways that control growth have been well characterized in recent years, little is known about how tissue mechanics affect the way cell divisions are coordinated. Indeed, in the context of epithelia, the cohesive nature of the tissue around each dividing cell opposes resistance to the local overpressure generated by the division, which induces a local mechanical stress. How these stresses sum up and distribute at the level of the tissue is not known. Most importantly, how they constrain the way the tissue grows is an open question. In order to address these questions, we study the growth of the wing imaginal disc, which is the precursor of the Drosophila adult wing. We culture excised imaginal discs under a confocal microscope and systematically analyse the shape of cells, looking for a signature of the internal forces that arise as the tissue grows.

Statistical morphometry revealed a systematic trend in stress distribution in the wing imaginal disc : cells in the center of the tissue are compressed and cells in the periphery are stretched. The center of the tissue further coincides with the sites where the two morphogens (Wingless and Decapentaplegic) that orchestrate growth have the highest concentration. Supported by computer simulations based on a vertex model for the mechanics of the tissue, we propose that the observed cell deformations arise from spatial variations of growth rates. Moreover, a systematic analysis of cell divisions revealed an overlapping pattern between cell division orientation and tissue stress in the disc periphery suggesting a link between mechanical tension of the tissue and orientation of divisions. Our results suggest a tight interplay between growth rate, tissue mechanics and orientation of growth during tissue morphogenesis.

Joint work with Hervé Rouault, & Thomas Lecuit

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