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. 2022 Apr 11;11:e57642. doi: 10.7554/eLife.57642

Figure 2. Early Convergence is uniform across regions.

Frames from time lapse movies of standard giant sandwich explants (A; Video 2*, left) or ventralized standard giants (B; Video 3*) after release from their constraining coverslips show uniform convergence of the IMZ. The upper limits of the upper and lower IMZ are indicated by dashed yellow and pink lines, respectively (A). To compare regional rates of convergence in such explants, the mediolateral extent of the dorsal (A, between blue pointers), lateral (between blue and magenta pointers), and ventral regions (between magenta and green pointers) of the IMZ were measured at times from Stage 10- and plotted with respect to initial width (Wt/Wi) in standard (dorsally centered) giants (n = 3–5 embryos per time point) (C) and ventrally centered giants (n = 4–5 embryos) (D). The convergence of the entire IMZ was also measured in giants from ventralized embryos (n = 3 embryos) (E); error bars = SEM. For C-E, the same explants were measured at sequential time points.

Figure 2—source data 1. Figure 2C, D source data: Relative live explant convergence vs. time.

Figure 2.

Figure 2—figure supplement 1. CT in giants without bottle cells and in Li+ Dorsoanteriorized giant sandwich explants.

Figure 2—figure supplement 1.

Giants made without bottle cells (A, Video 2, right) also show isotropic convergence and thickening of the IMZ throughout gastrulation in control embryos (stages and hours from the onset of gastrulation (G + Xh) indicated). Giants made from dorsoanteriorized embryos (B, Video 5) show isotropic convergence and thickening of the IMZ through at least Stage 10.5, when they begin isotropic convergence driving anterior-posterior extension; a thickened mass remains in the more animal portion of the IMZ and feeds into the converging and extending tissue.