Asymmetry in the frequency and position of mitosis in the mouse embryo epiblast at gastrulation

A

Representation of the position of the AVE‐opposed area (green) and the AVE‐adjacent area (pink) in WT (left) and RhoA ^VE‐deleted (right) embryos.

B, C

3D reconstruction (B) and confocal Z‐slice (C) of E6.25 WT (left) and RhoA ^VE‐deleted (right) embryos stained for an AVE marker (Cerberus 1, yellow), F‐actin (Phalloidin, grey) and mitosis (Phh3, magenta). Scale bar: 25 μm. Blue dotted line delimitates the pro‐amniotic cavity (apical side of the epiblast). Red arrowheads point to non‐apical mitosis. White lines delimitates the boundary between extraembryonic (up) and embryonic (down) regions of the embryo.

D

Percentage of AVE migration in WT and RhoA ^VE‐deleted mutants. Data information: values are shown as Mean ± SEM. WT: n = 31 embryos; RhoA ^VE‐deleted: n = 17 embryos. Normality was assessed using a Shapiro–Wilk test followed by a two‐tailed t‐test. ***P‐value ≤ 0.001.

E

Ratio of non‐apical mitosis (non‐apical Phh3 over total Phh3, normalized by the volume in μm³) in percentage, in AVE‐adjacent and AVE‐opposed regions from WT and RhoA ^VE‐deleted embryos. Normality was assessed using a Shapiro–Wilk test followed by Kruskal–Wallis test and Mann–Whitney tests. *P‐value ≤ 0.05, ***P‐value ≤ 0.001.

Figure 6. Non‐apical mitosis is a feature associated with the primitive streak.