Fig. 2

tbx16 mutants have reduced fluidity in an enlarged MPZ.

A Transmitted light lateral view of 10 SS embryos shows tbx16 mutants lack somites and have an enlarged DMZ/MPZ (arrowhead). B Orthogonal 10 µm confocal projections through 10 SS tbx16 mutant tailbud with nuclear label (white) from H2B-RFP mRNA injection. Dorsal tissue and MPZ are enlarged relative to wild-type, and the PSM is severely reduced (cf. wild-type in Fig. 1B). Representative image from 5 tbx16^−/− embryos analyzed. C Posterior body elongation speed is no different in tbx16 mutants compared to siblings (N = 11 embryos for sibling; N = 9 embryos for tbx16^−/−; center line: mean; box: SE; whiskers: SD). D Normalized MSRD in the tbx16 mutant (For wild-type, n_p = 3370 from N = 6, and for tbx16^−/−, n_p = 1716 from N = 6; shading: SE). E Ferrofluid oil droplet (magenta) embedded in tbx16^−/− MPZ injected with mem-GFP mRNA to label cell membranes (green). Panels show droplet before (0 min), at maximum deformation (15 min) and after a subsequent 15 min relaxation (30 min); the residual deformation after 15 min is used to calculate residual stress. Representative image from 11 tbx16^−/− embryos analyzed. F Residual stress in tbx16 mutant MPZ compared to siblings (N = 8 embryos for sibling and N = 11 embryos for tbx16^−/−; center line: mean; box: SE; whiskers: SD). G Velocity temporal correlation in tbx16 mutants (For wild-type, n_t = 3831 from N = 6, and for tbx16^−/−, n_t = 1925 from N = 6; shading: SE). H Fluidity index of tbx16 mutant tailbuds (average fluidity index map from N = 5 embryos). I 2D velocity field in a tbx16 mutant. J Maximum intensity projection of a dorsal view of a tbx16 mutant tailbud with manually segmented and tracked nuclei showing that posterior movement of dorsal tissue relative to ventral tissue is reduced (cf. wild-type in Fig. 1K). Representative image from 3 tbx16^−/− embryos analyzed. Scale bar: 400 µm (A), 100 µm (B, J), 10 µm (E). Source data are provided as a Source Data file.