Fig. 8. Rescue of anterior head truncation in Dkk1 null mice by reduced expression of Lrp6. (A) Single mutants that are null for Dkk1 lack anterior structures of the head, which results in neonatal lethality. The null phenotype is rescued in double mutants which are heterozygous for the null allele of Lrp6, shown at E16.5 (B) and P30 (C). Lateral deviation of the lumbar vertebrae in the P30 double mutant is evident in the skeletal preparation (D).