“…(2) Except for trunk axial muscles, myoblasts leave their sites of initial differentiation and move, usually as aggregated cohorts, into peripheral regions (reviewed by: Noden & Francis‐West, ; Tzahor & Evans, ). This process and (3) the subsequent myotube alignment, segregation of individual muscles, and attachment of myotubes to definitive connective tissues require “instructive” interactions from adjacent connective tissues (limbs: Kardon, ; Kardon, Harfe, & Tabin, ; Robson, Kara, Crawley, & Tickle, ; diaphragm: Merrell et al, ; jaw: McGurk et al, ; reviewed by: Chal & Pourquié, ; Deries & Thorsteinsdóttir, ). In some cases, those interactions are associated with differentiating cartilages or tendons, but often the cues are operating at earlier stages and are more cryptic, identified only through analyses of local transcription factors, for example, Tbx4 and Tbx5 genes in limb mesenchyme (Hasson et al, ).…”