Fig. 6: The fixed proportion of EPI:PrE cells without cell fate-switching challenges precision in ICM patterning.
From: Coupling of cell shape, matrix and tissue dynamics ensures embryonic patterning robustness
a, Proportion of cell fates in the ICM in embryos under different conditions during development. One-way ANOVA, P = 0.085. n = 19, 29, 21 and 32 embryos for the different groups, respectively. Mean PrE proportion of 0.605 ± 0.078. b, Limited contribution of position sensing and cell fate-switching in E3.75 ICMs to final patterning of the ICMs. Consecutive time-lapse images from isolated ICMs expressing PdgfraH2B-GFP and the corresponding lineage tree for the ICM. White dotted line marks ICM boundary. t = 00:00 corresponds to start of live-imaging at stage E3.5 + 3 h, following completion of immunosurgery. Lineage tree of an isolated ICM from single-cell tracking in Fig. 1c,d. Yellow arrowhead, inside cell that increases PdgfraH2B-GFP expression after moving to the surface and its lineage. Stacked bar plots indicating frequency of position sensing and fate-switching contributing to the final EPI/PrE cell fates. c, Schematic and immunofluorescence images of size-manipulated blastocysts at stage E4.5. White arrowheads indicate ectopic EPI cells in smaller blastocysts and ectopic PrE cells in larger blastocysts. d, Number of PrE cells in the ICM in E4.5 size-manipulated blastocysts. Dotted line shows linear regression with Pearson’s R = 0.98; P = 1.18 × 10−134. PrE proportion of 0.599 ± 0.006. n = 26 embryos for 2/8×, 29 embryos for 3/8×, 24 embryos for 4/8×, 29 embryos for 1×, 17 embryos for 2×, 18 embryos for 3× and 10 embryos for 4× size ratios. e, Quantification of ectopic EPI/PrE cells in size-manipulated E4.5 blastocysts. The number of ectopic cells is plotted as a function of total number of cells in the ICM. f, Left, schematic of chimera experiments to test feedback between cell fate and position in the ICM. Right, immunofluorescence images of 2× chimeric E4.5 blastocysts composed of cells from WT + WT combination (left column) and WT + Myh9+/− combination (right column). White arrowhead marks GATA4-negative cells on the ICM surface. g, Quantification of number of GATA4-negative cells on the cavity surface in WT + WT combination and WT + Myh9+/− combination of E4.5 chimeric blastocysts. n = 40 and 19 embryos for the two groups, respectively. Two-sided Mann–Whitney U-test, P = 2.82 × 10−5. Scale bars, 20 μm. *P ≤ 0.05, **P ≤ 0.01, ***P ≤ 0.001.
