Expression of epiblast markers in wild-type, Cripto, and Cripto; Cryptic mutants. (AC) Expression of Oct4 at 5.5 dpc; note the down-regulation in the Cripto−/−; Cryptic−/− double mutant (arrow). (D–F) Oct4 is expressed at 6.5 dpc in the wild-type epiblast (D), but not in the Cripto−/− or Cripto−/−; Cryptic−/− mutants (E, F). (G–I) Expression of Nanog at 6.5 dpc is down-regulated in the Cripto−/− mutant, but is absent in the Cripto−/−; Cryptic−/− double mutant. Nanog expression is localized to the posterior epiblast in the wild-type embryo (G), but is proximally localized in the Cripto−/− mutant (arrow in H), which lacks anterior-posterior polarity. Scale bars correspond to 100 microns. Abbreviations: epi, epiblast; exe, extraembryonic ectoderm; ve, visceral endoderm.