Fig. 2: Absence of ASPP2 expression leads to structural defects in the epiblast.

a Immunofluorescence of wild type and ASPP2^ΔE4/ΔE4 E6.5 embryos using an anti-Par6 antibody. The phenotypic variability of ASPP2^ΔE4/ΔE4 embryos is illustrated, with embryos either lacking cavities (middle row, five out of nine embryos) or exhibiting smaller cavities (bottom row, four out of nine embryos). The green dashed line highlights the ectopic accumulation of cells in the epiblast of ASPP2^ΔE4/ΔE4 embryos. b Magnification of the corresponding regions shown in panel a. Blue arrowheads highlight the enrichment of F-actin at the apical junctions in the epiblast. Note how F-actin is not enriched at the apical junctions but is instead more homogenously distributed across the apical surface of epiblast cells in ASPP2^ΔE4/ΔE4 embryos (orange arrowhead). The insets within images are 2x magnifications of the corresponding dashed areas. c Quantification of F-actin signal intensity along the apical surface of epiblast cells of wild type (n = 3 embryos, five measurements per embryo) and ASPP2^ΔE4/ΔE4 embryos (n = 3 embryos, five measurements per embryo). Measurements were made on cross-sections along the apical domain of individual epiblast cells from apical junction to an apical junction (represented with a blue background in the graph). The 95% confidence interval is represented by the grey area. See material and methods for details. d Immunofluorescence of wild type (representative images from eight embryos) and ASPP2^ΔE4/ΔE4 E5.5 embryos (representative images from five embryos) using an anti-Laminin antibody. e Magnification of the corresponding dashed areas in panel d. f Immunofluorescence of wild type (representative images from seven embryos) and ASPP2^ΔE4/ΔE4 (representative images from two embryos) E6.5 embryos using an anti-SCRIB antibody. g Magnification of the corresponding dashed areas in panel f. Green arrowheads highlight basolateral SCRIB. Note the enrichment of SCRIB at the apical junctions in the epiblast of wild type embryos (blue arrowhead) and its absence in the corresponding localisation in ASPP2^ΔE4/ΔE4 embryos (orange arrowhead). Nuclei and the F-actin cytoskeleton were visualised with DAPI and Phalloidin, respectively. Scale bars: 20 μm. Source data are provided as a Source Data file.