Fig. 2.

Pelvic skeletal phenotypes of compound Pbx family member mutants at E13.5 as assessed using Alcian blue and Alizarin red staining and OPT. A: Compared to WT HL (left panel): Pbx1^−/− embryos exhibit either absent or detached ilia (red inset, red asterisk), and reduced pubis (red arrow) and ischia (red arrowhead); Pbx1^−/−;Pbx2^+/− mutants lack ilia and pubis and display rudimentary ischia (red arrowheads in main panel and insets). Insets show additional embryos acquired via breeding schemes described in Materials and Methods and Results. Lower red inset depicts the presence of a small tissue rudiment (blue arrowhead), often found in mutants repeated out-crossed to Black Swiss (BLSW); Pbx1^−/−;Pbx3^+/− mutants phenocopy single Pbx1 homozygotes in all defects (red asterisk, arrows, and arrowheads), and reveal that Pbx3, in this mutant model, is not required for distal HL development. B: OPT of WT (white symbols) and select Pbx family member mutants highlights defects illustrated above (red symbols), and that Pbx1^−/−;Pbx2^+/− mutants exhibit only truncated ischial rudiments (red arrowhead).