Fig. 11.

Behaviour of muscle precursors electroporated with a dominant negative Lbx1 construct. (A–D) Lateral views, rostral to the top, and (Ci, Di) cross sections, dorsal to the top, of somites electroporated with the pCaβGFP control vector (A, C, Ci) or the vector encoding a dominant negative (dn) Lbx1-VP16 construct (B, D, Di). Cells harbouring the constructs are shown in blue; the lateral edges of somites are indicated by black lines in (C, Ci, D, Di). Cells from the lateral edge of control-electroporated somites emigrated normally, both at occipital (A, arrows) or at forelimb levels (C, Ci; arrowheads). When the dnLbx1 construct was used, muscle precursors at forelimb levels failed to emigrate (D, Di; open arrowheads). In contrast, occipital muscle precursors, albeit delayed, projected along the normal path of HMP (B, arrow). Abbreviations: hy, hyoid arch.