S. Härtel, J. Jara, C.G. Lemus, M.L. Concha
Ed. João Manuel Tavares & Jorge Nata, Taylor and Francis Group, ISBN: 9780415433495, pp: 215-220.

We applied in vivo confocal microscopy of GFP-transgenic zebrafish in combination with 3D image analyses to study the asymmetric morphogenesis of the diencephalic parapineal organ on a supra-cellular, cellular, and sub-cellular level. Following a rough manual segmentation of the respective regions of interest (ROIs), the morphology of generated surface meshes was refined by an active surface model which it-eratively adjusts the mesh towards the morphology of the cellular structures. This procedure is essential for a precise morpho-topological analysis, mostly because of the adversarial diffraction limited resolution in the z-dimension of confocal image stacks. 3D Morphology and topology of the reconstructed cellular and supra-cellular structures during morphogenesis was quantified by principal axis transformations and 3D moment in-variants. Our data indicates that migration of the parapineal organ is accompanied by a rapid transition be-tween predominantly parallel cell orientations towards predominantly perpendicular orientations, a phenome-non which requires a precise control of cell shape and polarity. The orientational transition is followed by a phase of polarized cell motility in which membrane protrusions in the form of blebs and filopodia become ori-ented in the direction of the asymmetric migration. The morpho-topological descriptors unveil information that is not perceptible for a direct visual analysis of the microscopical data sets. This approach becomes essen-tial to access morphogenetic mechanisms which control asymmetry and migration.

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