Fig. 2. Distribution of nuclear ß-catenin, P-MAPK and P-Smads during blastula stages. Because there are only few nuclei per section at early stages, nuclear images of several sections were superimposed (number of sections: stages 8 and 8.5=5; stage 9=3-4; stage 9.5=3). ß-catenin and P-MAPK images are from double-stained sections. Arrows and arrowheads point at particular aspects of the patterns discussed in the text.