Fig. 1. Mating scheme used to generate embryos lacking either maternal E-cadherin or ß-catenin. To generate females whose oocytes would be deficient in either ß-catenin or E-cadherin, homozygous floxed females (Floxed/Floxed: [ß^F/ß^F] or [E^F/E^F]) of each line were crossed with homozygous C57BL/6-Tg(Zp3-cre)93Knw males (cre/cre) containing a cre-recombinase transgene under control of the Zp3 promoter. Males hemizygous for the Zp3-cre transgene and heterozygous for either floxed allele (Floxed/+;cre/Ø: [ß^F/ß;cre/Ø] or [E^F/E;cre/Ø]), were backcrossed to females homozygous for the ß-catenin or E-cadherin floxed alleles (Floxed/Floxed: [ß^F/ß^F] or [E^F/E^F]). This generated females homozygous for either floxed allele and heterozygous for Zp3-cre (Floxed/Floxed;cre/Ø: [ß^F/ß^F;cre/Ø] or [E^F/E^F;cre/Ø]) that produced oocytes deficient in either ß-catenin or E-cadherin. These females were crossed to wild-type C57BL/6J males to generate embryos lacking maternal ß-catenin or E-cadherin, but with a wild-type paternal allele (Floxed^del/+; del=deleted floxed). Control females homozygous for either floxed allele, but not carrying the Zp3-cre transgene (Floxed/+: [ß^F/ß^F;Ø/Ø] or [E^F/E^F;Ø/Ø]) were mated to wild-type C57BL/6J males (+/+; Ø;Ø) to generate control embryos. To determine whether presence of the Zp3-cre transgene would influence the outcome of embryo development, control females heterozygous for either floxed allele and hemizygous for Zp3-cre (Floxed/+;cre/Ø: [ß^F/ß;cre/Ø] or [E^F/E;cre/Ø]) were also mated to wild-type C57BL/6J males. Mice homozygous for both E-cadherin and ß-catenin floxed alleles were bred by intercrossing mice homozygous for either ß-catenin or E-cadherin floxed alleles ([ß^F/ß^F] or [E^F/E^F]), and crossing their offspring inter se. To obtain females homozygous for both floxed alleles and hemizygous for the Zp3-cre transgene, females homozygous for both floxed alleles were crossed to males homozygous for both floxed alleles, and hemizygous for the Zp3-cre transgene [ß^F/ß^F;E^F/E^F;cre/Ø]. This cross produced [ß^F/ß^F;E^F/E^F;cre/Ø] females that gave rise to oocytes deficient in both ß-catenin and E-cadherin.