A division that leaves daughters with mirrored allotments of Pard3 (green) causes one cell to cross (left) the midline (yellow line). Cells fail to cross (right) in the presence of a mutant Pard3.

CLARKE/MACMILLAN

By sending apical proteins to the division plane, epithelial cells create mirror image daughters, say Marcel Tawk, Jonathan Clarke (UCL, London, UK), and colleagues. This mirror symmetry helps form the zebrafish neural tube.

Fish form neural tubes by hollowing out a solid rod of cells. Within the rod, cells are elongated and occupy all positions across the rod diameter, including the midline. During tube formation, cells must move away from the midline, where the lumen will form. At the same time, the rod cells become polarized such that their future apical side is adjacent to the lumen.

Tawk et al. examined these changes by fluorescently tagging the apical marker Pard3, whose...

The Rockefeller University Press
2007
The Rockefeller University Press
2007
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