Fig. 4. Proportional contribution of labelled cells to mural trophectoderm (M) against relative contribution of labelled cells to trophectoderm versus ICM (F). The derivation of the values M and F is described in the text. (A) Values of M and F for a group of 16 experimental embryos injected at the 4-cell stage with dsPar3 RNA (pale blue). A group of 14 control embryos were injected with dsGFP RNA (orange). (B) Values of M and F for a group of 25 experimental embryos injected at the 4-cell stage with mRNA for dominant negative aPKC (blue). A group of 26 embryos were injected with mRNA for wild-type aPKC (purple). (C) Combined groups of control embryos injected with DsRed mRNA at either the 4- or 8-cell stage (red and pink, respectively) or dsGFP RNA at the 4-cell stage (orange). (C, left panel) A control embryo (corresponding to the indicated data point) representing a clone of cells making a major contribution to the ICM and also the polar trophectoderm. (C, right panel) A control embryo (corresponding to the indicated data point) representing a clone of cells contributing predominantly to mural trophectoderm. Bar, 10 µm. Positive rank (Spearman) correlation coefficients were obtained for the values of F and M in both the dsGFP and DsRed control groups (r=0.44, 0.10<P< 0.20; and r=0.37, P<0.05, respectively). Control blastomeres injected with DsRed at the 8-cell stage, or with wild-type aPKC at the 4-cell stage, also gave respective positive correlation coefficients of r=0.52 (0.10<P< 0.20) and r=0.35 (0.05<P< 0.10). When all control groups were combined (panel C), the correlation was highly significant (r=0.51, P<0.001).