Fig. 3. Migratory behaviour of cells from the chick somitic dorsomedial lip. (A-C) DiI labelling of the dorsomedial lip (dml) of somite X (SX) (A, schematic) shows that dml cells (B, time zero, transverse section) give rise (C) to two distinct populations that migrate in opposite directions after 24 hours (red arrows). (D-F) Transplantation of five left-side somites, from a donor to the right side of a host embryo (D, schematic). (E-G) Hybridization with Wnt11 probe shows that after 24 hours, the Wnt11 cells have migrated from the transposed dorsomedial lip (tdml) over the entire dermomyotome towards the midline (m). This is seen in an external view of the right side (E) and in a transversal section (F, arrows). A higher magnification (G) clearly shows the migration of the cells from the tdml under the ectoderm (red arrows). nc, notochord; nt, neural tube; PSM, presomitic mesoderm. Scale bars: 50 µm in B,C; 300 µm in E; 70 µm in F,G.