Fig. 9. Fig. 9, Fig. 10, Fig. 11, Fig. 12 are summary diagrams of ß-catenin, P-MAPK, Smad2 and Smad1 pattern during early development, respectively. Each drawing represents an average pattern obtained by analysis of several sections. The relative intensities between various stages were compared using pseudocolors images (see Fig. 1). Red is strongest, pale yellow is very weak/inhomogeneous. The spotted pattern of Smad2 at stage 8 indicates a very heterogeneous signal. All sections are sagittal unless stated otherwise. eq, equatorial; ps, parasagittal; tr, transversal.