Fig. 5. Hox expression during axial patterning. The anterior boundary of Hoxb6 expression at E11.5 is the same in control (A) and Hox5 paralogous mutant (B) mice. The anterior boundary of Hoxd11 expression in control (C) and Hox10 paralogous mutants (D) is also equivalent. (E-M) A Neo^r probe was used to demonstrate the anterior expression boundaries of the entire paralogous group in triple heterozygous animals (in the case of Hox5 and Hox6 embryos) or quadruple heterozygous mutants (for Hox9 embryos), none of which have a phenotype. Each mutant allele has Neo^r inserted into the Hox coding sequence. Somite anterior expression limits are marked with a white arrow and lateral plate anterior expression limits are marked with a black arrow. (The anterior expression limit for the neural tube, marked with a black arrowhead, is often far anterior to the somite expression boundary as published for the individual Hox genes referenced in the text.) E,F,H,I,K,L, embryos shown in lateral and dorsal view; G,J,M, embryos shown in lateral view only.