Fig. 9.

A Shox2-coordinated transcription program for stylopod patterning. In the developing proximal limb, juxtaposition of the proximal TALE-dominant domain and the relative distal Shox2-dominant domain (where Shox2 is the dominant identity and the dominant form of Shox2/TALE co-occupancy on their co-occupied enhancers) results in transcription that is favorable for osteogenesis of the perichondial Shox2⁺ progenitor cells. These cells simultaneously instruct the chondrogenic differentiation of stylopodial skeleton primordia (SP) and undergo osteogenic differentiation to provide osteoblasts to form bone.