The cellular mechanisms driving primitive streak formation in the chick embryo
Prof. Kees Weijer (University of Dundee)
Thursday 18th February, 2016 14:00-15:00 Maths 203
Primitive streak formation is an essential stage in the embryonic development of amniotes including humans. It is characterised by embryo wide tissue reorganization and deformation which are driven by coordinated cell shape changes and rearrangements. To be able to image the detailed cell behaviors of >200.000 cells we have designed and build a light sheet microscope (LSM) dedicated to imaging large flat samples. Using this LSM we show that the large scale tissue deformations resulting in the formation the primitive streak in the chick embryo are driven by anisotropic pulling forces generated by cell shape changes and local rearrangements of mesendoderm cells in the epiblast. Cell rearrangements are mediated by sequential, directional contraction of temporary aligned apical junctions in asymmetrically shaped neighboring cells, a process driven by apical acto-myosin II cables . We also image the detailed cell behaviors during the ingression of mesoderm cells into the primitive streak. Understanding how these cellular behaviours are integrated to result into complex tissue shape changes will require extensive modeling.
[1.] Rozbicki, E., et al., Myosin-II-mediated cell shape changes and cell intercalation contribute to primitive streak formation. Nat Cell Biol, 2015. 17(4): p. 397-408.