X-Gal staining of whole heterozygote Cdan1^gt/wt embryos. (A) Whole mounts at different stages of development. The only homozygous embryo Cdan1^gt/gt, as shown in Table 1, obtained in this study clearly shows strong X-Gal staining, demonstrating Cdan1 expression from both gene-trapped alleles. (B) Intense X-Gal staining of yolk sac mesoderm-blood islands in Cdan1^gt/wt embryos at E7.5 in cross section. (C) Intense X-Gal staining of a wide range of cell populations in Cdan1^gt/wt embryos at E10.5. Bro indicates bronchus; Gu, gut; and YS, yolk sac.