Fig. 4. Myogenic differentiation markers co-localise with cranial Lbx1 expression. Lateral views and cross sections of HH19/20 chick heads as in Fig. 3. Cranial ganglia in A-D,F-I are highlighted with Isl1 (red). (A,B) Myf5 labels all cranial muscle precursors in the process of differentiation. Note that beneath the trigeminal ganglion, Myf5 stains the anlage of the lateral rectus muscle (arrow, lr). (C,D) MyoD, (F,G) Pitx3 and (H,I) R-Cadherin all resemble the expression pattern of Myf5, with expression evident in the cells beneath the trigeminal ganglion, and in the mandibular and hyoid arches. (E,J) Double labelling depicting Lbx1 in blue and MyoD (E) or R-Cadherin (J) in red. Note that transcripts for both myogenic markers and Lbx1 co-localise (arrows). do, dorsal oblique; dr, dorsal rectus; hy, hyoid arch; lr, lateral rectus; ma, mandibular arch; t, tongue muscle precursors; vr, ventral rectus. Scale bars: in A, 500 µm in A,C,F,H; in B, 100 µm in B,D,G,I; in E, 100 µm in E,J.
