The second anniversary of my request for help to position the four vortices Fleury claims is rapidly approaching and I was looking around for something relevant to make a celebration poster.
I opened The Mechanisms Underlying Primitive Streak Formation in the Chick Embryo, by Manli Chuai and Cornelis J. Weijer1 for inspiration and of course Fleury’s webpage with his english short presentation.
Chuai & Weijer propose a simple model fitting their observations.
This is a rearrangement of elements from figure 1 (left panels) showing the transient vortices observed at the first stages of gastrulation at the epiblast level, bright field and epifluorescence, the marker being GFP expressed post-transfection and figure 3 (right panels) presenting a schema of their chemotactic model and the analogy with a hydrodynamic flow.
This is what Fleury describes as:
The usual picture of a development oriented in the antero-posterior direction is wrong. The recent dipolar description by Chuai, Weijer and co-workers is also wrong.
By saying so, he implies that the model don’t fit reality.
Maybe he failed to observe that the model proposed above include an area where Vx=Vy=0 at the center of Koller’s Sickle (KS) 🙂
How Fleury’s model fit reality? One may think that it must be better.
The left panels as previously described, the right panel from Fleury’s model, tilted to align the axis to the one of the microscope images, the lower one being a superposition with the actual data. Pretty much the same frame of Weijer’s et al. time-lapse movie as the one Fleury used to position the missing vortices two years ago [fr but the images are international].
That would place the hindlimbs, according to Fleury’s, behind the KS!
A larger picture with the missing vortices annotated L2/R2:
not only “no L2/R2 – no hindlimbs” but also “if L2/R2, then hindlimbs behind the embryo!”
That doesn’t bother Fleury who prefers his model, coming out from the platonician space of forms, with the two
invisibleimaginary vortices, instead of one quite realistic.
Make your mind. My preference goes to the one that stand reality check.
And if your name is Vincent Fleury and you are a theoretical physicist try to explain that.
1 Current Topics in Developmental Biology, Vol. 81 doi: 10.1016/S0070-2153(07)81004-0
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