THESE ARE A FEW IMAGES AND ANIMATIONS FOR THE COURSE IN SECOND LIFE (EMBRYO PHYSICS) AND ALSO SHOWN AT THE SYMPOSIUM

"MORPHOGENESIS IN LIVING SYSTEMS"

This is an in vivo image of an embryo at the early gastrula stage. The box shows the vector field. The green tracks represent 30' of tracking of the blue cross, overlaid on the starting frame. The frames were acquired at a rate of 30 secs. The magnification is 4x on the binocular Leica MZFLIII, + a 0.63 lens on the trinocular tube, and the data are acquired by a 1/2" CCD camera, high sensitivity monochrome from Watec.
This is an in vivo picture of the flow at the time of formation of Hensen's node. The box shows the flow pattern. A brutal caudal pull is exterted on the ectoderm, which winds the tissue in the caudal direction.
This is an in vivo picture of the flow at the time of formation of Hensen's node. The box shows the flow pattern. At this stage, the caudal vortex is very well seen. It revolves and is translated caudally by the entire movement itself.
This is an in vivo picture of the flow at the time of formation of the lateral plate. The box shows the flow pattern. The winding brings the tissue towards the median axis, while the median axis extends. The entire visco-elastic fields ends in segregation of the median axis, and the lateral plates, by a fold occuring visco-elastically. Meanwhile, the lateral plates start to rpotrude in 3D.
This is an in vivo picture of the flow at the neural crest stage. The box shows the flow pattern. The hyperbolic symmetry breaking is passed to furtehr stages, as the embryo continues to fold. One cannot sperak of "stages", it is a continuous visco-elastic folding, whose main feature (hyperbolic winding) is inherited by all stages continuously.
In vivo image at the 3 somites stage, and the flow. The rotation in the pelvic area is very conspicuous. The median axis extends in a straightforward fashion, but in a bi-directional fashion. The tissue is sheared laterally. This induces a solid body vortex core along the pelvic area (see movies). The region of somite formation coincides with the hyperbolic point.
In vivo image at the seven somites stage.
In vivo image at the eight somites stage.
Twelve somites stage.
Thirteen somites stage.
Animations continue. See more images and animations Go to mathematical formulas Mathematics of vortex flows

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La citation de la page : "Nous avons beau faire, l'amour-propre est toujours le mobile plus ou moins caché de nos actions", Emilie du Châtelet.