Fig. 3. Specific functions of Wnt6 and Wnt1 in the epithelialisation and patterning of somites. (A) Schematic of the procedure: separation of the PSM from overlying ectoderm with a membrane (blue) after the injection of Wnt-expressing cells (in red) and followed by 24 hours in culture. (B) Transverse section through F. (C) Transverse section through M. (D-I) Expression of markers after the injection of Wnt6-(D-I) and Wnt1-expressing (J-O) cells: (D) Fz1; (E) Fz2; (F) Fz7; (G) pax3; (H) paraxis; (I) Wnt11. Wnt-expressing cells were stained with fixable CM Tracker DiI; their exact position, defined under UV examination, was recorded and is indicated in each panel by broken lines. The corners of the impermeable membranes are indicated in each embryo.