Fig. 4

Pitx2c promotes oriented, persistent endodermal cell migration.

(a–e) Time-lapse imaging was performed to assess the early migration (random walk pattern from 6.5 to 7.5 hpf) and (f–j) late migration (oriented and persistent pattern from 8 to 9 hpf) of endodermal cells labelled by Tg(sox17:GFP) expression. Representative tracks of endodermal cells are shown from 6.5 to 7.5 hpf (a, b) and from 8 to 9 hpf (f, g) from wild-type and MZpitx2c mutant embryos. Quantification of speed (c, h), track displacement (d, i), and track straightness (e, j) from wild-type and MZpitx2c mutant embryos are shown in the graphs below (n > 3 embryos, 20–40 tracks per embryo). While early random walk motions are similar to wild types (a–e), later endodermal cell persistence and directional migration are significantly affected in MZpitx2c mutants (f–j). (k–m) Analysis of anterior endodermal derivatives at 24 hpf in wild-type (k) and MZpitx2c mutant (l) embryos. The width of the endoderm (shown by the yellow dashed lines) was measured at the level of the fifth pharyngeal pouch and quantified from at least eight embryos (m). Increased endoderm width is observed in MZpitx2c mutants compared to wild types. *p<0.05, ***p<0.001 by unpaired t-test. Scale bars, 40 μm.