Fig. 3. The presence of the eye is not required for eye muscle differentiation and specification. (A) Scheme of eye ablation at HH10; dorsal view, anterior to the top. The optic placode and the region of the forebrain delivering the optic cup were removed. Pink: unsegmented head mesoderm. (B-E) Lateral views of HH19 heads; anterior to the top, dorsal to the right for unoperated sides (B,D), dorsal to the left for operated sides (C,E). (B-E) Brown staining: Pax6 antibody staining detecting strong expression in the telencephalon (t), eye, neural tube (nt)/hindbrain. Note, in operated embryos the eye is missing; only the rest of the optic stalk remained (C,E, open arrowhead). (B,C) Lbx1 (blue staining) revealing normal lateral rectus anlagen. (D,E) Also Myf5 expression (blue) is wild type. Scale bar: 200 µm. do, dorsal oblique EOM; dr, dorsal rectus EOM; hm, unsegmented head mesoderm; hy, hyoid arch; lr, lateral rectus EOM; ma, mandibular arch; nt, neural tube; ov, otic vesicle; t, telencephalon; vr, ventral rectus EOM.