Derivatives of r2 dorsal neural tube have a characteristic migration pattern correlated to maintenance of endogenous Hoxa2 expression (A) Flatmount of a fate-map chimaera at embryonic day (E) 6 (e6), in which quail r2 was orthotopically grafted into rhombomere 2 (r2) of a chick host. At E6, in flatmount, quail derivatives (brown) condense primarily in a single ventrolateral nucleus. (B) In transverse section, r2 migrants can be seen to settle in a subpial location similar to that of ventral derivatives in r1. (C) When transplanted into r1, quail r2 cells contribute to the EGL while maintaining a sparse ventral contribution. (D) When analysed by in situ hybridisation at E4 (e4), r2 grafted into r1 has lost its endogenous Hoxa2 expression (blue). Scale bar = 100 μm.