Fig. 3. Axis duplications in Nap1^khlo mutants. (A-C) T expression. (A) Wild-type embryos have a single allantois, and a brachyury-expressing primitive streak and notochord at E8.5. Approximately one quarter of Nap1^khlo homozygotes showed a partial or complete duplication of the anteroposterior axis. In some mutants, the allantois was duplicated (B, asterisk), whereas nearly the entire body axis, including the primitive streak and notochord, was duplicated in the most severely affected Nap1^khlo mutants (C). (D,E) Tbx4 expression marks the allantois in a wild-type embryo (D) and in a Nap1^khlo mutant with an ectopic allantois (E). Anterior is up in all panels.