Fig. 4. Innervation does not control eye muscle differentiation and specification. Internal views of HH20 bisected chick heads; anterior to the top, dorsal to the left in A and right in B. Embryo stained for Paraxis expression (blue); nervous system traced with RMO270 in brown. (A) Unoperated control side. Note the abducens nerve (cranial nerve VI) with nerve rootlets in rhombomeres 5 and 6 (arrowheads) and axons having entered the Paraxis domain (arrow). (B) Rhombomeres 5/6 ablated side. The abducens nerve is missing (open arrowhead), but Paraxis is expressed normally. Scale bar: 200 µm. r, rhombomere; VI, abducens nerve.