a, Representative haematoxylin and eosin (H&E) and immunohistochemistry staining on E7.5 embryos with indicated genotype (magnification, ×20). b, Messenger RNA expression levels of Slc7a11 in E9.5 embryos with indicated genotype (error bars, s.d.; n = 3 for p533KR/3KRMdm2+/+ and n = 5 for all other genotypes). c, Representative morphologies of E14.5 embryos treated with either dimethyl sulfoxide or ferr-1 (magnification, ×1.5). d, Messenger RNA expression levels of Ptgs2 determined similarly as in b. All data were repeated independently at least three times and representatives are shown.