Figure 2.

Generation of an allelic series of EGF mutations in DLL1 and external phenotypes. (A) Structure of Dll1 before and after homologous recombination and of the targeting vector. Black boxes indicate coding and white boxes noncoding regions of Dll1. The cDNA portion is outlined in red. (B) Morphology of wild-type 129Sv/ImJ embryos and mice and of isogenic embryos and mice homozygous for the Dll1 alleles. Alleles are indicated at the left, developmental stages at the top. Arrows in y, z, zd, ze, zza and zzb point to shortened tails; arrowheads in zk and zw point to tail kinks.