Fig. 1. Scanning electron micrographs of wild-type (A,C) and Tbx5^del/del (B,D) embryos at E9. Limb bud outgrowth is apparent in wild-type but not in Tbx5^del/del embryos (arrows in A,B, asterisks in C,D). Lateral plate mesoderm is seen in embryo of either genotype as a ridge along the side of the embryo.