Fig. 7. Tetraploid cells can rescue abnormal morphologies of NT embryos at E7. (A,B) Normal chimaeras made by aggregation of a NT embryo and a tetraploid, GFP-expressing, embryo developed from a fertilised zygote. (C) Tetraploid embryo developed after disappearance of NT blastomeres. The embryo in A is at early streak stage; the embryo in B is at late-streak stage. (Inset) Higher magnification of C showing that all epiblast cells express GFP. Scale bars: 100 µm.