Fig. 1. Expression of Lbx1 in the pre-otic head mesenchyme. (A-D) HH16-23 chick heads stained for Lbx1 expression; lateral views, anterior towards the top. (A) Lbx1 expression in the head mesenchyme rostral to the otic vesicle commences at HH16 (arrow). (B) At HH19, while Lbx1-expressing, somitic tongue muscle precursors (t) migrate towards the mandibular arch, Lbx1 cells in the cranial mesenchyme remain in residence (arrow). (C) Higher magnification of the Lbx1 domain at HH20. Using an anti neurofilament antibody to identify the cranial ganglia (brown), we located the Lbx1-positive cells (arrow) beneath the developing trigeminal (Vth) ganglion at the axial level of rhombomere 2 (r2). (D) The cranial Lbx1 spot is still in the same location by HH23, by which time it has been overgrown by the eye. m, midbrain; ma; mandibular arch; nt, neural tube; ov, otic vesicle; r2, rhombomere 2; t, tongue muscle precursors; V, trigeminal ganglion; VII, facial ganglion. Scale bars: 500 µm in A,B,D; 200 µm in C.
