a, qRT–PCR analysis of Chd7 expression in untreated MEFs derived from E13.5 p53+/− and p5325,26,53,54/+ embryos. The graphs indicate the mean ± s.d. from four independent MEF lines after normalization to β-actin gene expression. ns, not significant. b, Left, Schematic of NCC differentiation. Right, Representative qRT–PCR analysis of NCC markers in NCC-like cells differentiated from Chd7+/+ and Chd7−/− (whi/whi) mouse embryonic stem cells normalized to β-actin gene expression and relative to matched embryonic stem cells. c, Haematoxylin and eosin stained E10.5 Chd7+/+p53+/− (control), Chd7−/−p53+/+ and Chd7−/−p53+/− embryos. The Chd7−/−p53+/+ embryo shown is necrotic, as evidenced by cellular autolysis. Original magnification, ×32. d, Close-up image of heart region denoted by red box in panel c, in E10.5 Chd7+/+p53+/− (control) and Chd7−/−p53+/− embryos. Original magnification, ×100.