Figure 3.

The Fmn^Δ10.24 and ld^In2 mutations are allelic to Gre^ΔORF by disrupting cis regulation of Gremlin in the limb bud mesenchyme. (A–D) Forelimb skeletal phenotypes of compound heterozygous mice. (E,F) Gremlin is no longer expressed in the limb bud mesenchyme of Fmn^Δ10.24/+; Gre^ΔORF/+ (E) and ld^In2/+; Gre^ΔORF/+ (F) compound heterozygous embryos. (G–J) Formin remains expressed in the limb bud mesenchyme of ld^In2/In2 (G), Gre^ΔORF/ΔORF (H), Fmn^Δ10.24/+; Gre^ΔORF/+ (I), and ld^In2/+; Gre^ΔORF/+ (J) compound heterozygous embryos. Note: Samples G–J were pretreated prior to whole mount in situ hybridization for optimal detection of Formin transcripts in the mesenchyme. Such pretreatment results in loss of the AER. Genotypes are indicated as defined in the legend for Figure 2A.