In Cited1Cre;Fgf8f/Δ;Fgf17Δ/Δ;Fgf18f/+ embryos, the omphalocele incidence was very infrequent and equivalent to controls (one individual in each genotype) (Fig. 6J), suggesting that the loss of Fgf8 expression in the somites (Fig. 6F) does not cause a VW closure defect and therefore the Fgf8 requirement is in the PSM. This evidence concerns the gene FGF8 and omphalocele.