Fig. 2. Do the VegT and Wnt pathways act separately in the vegetal mass to produce a mesodermal signal and a dorsal signal respectively? (A) The design of the experiment shown in C. The equatorial regions of ß-catenin^– embryos at stage 8 were dissected and co-cultured for 2 hours with wild-type, ß-catenin^– or VegT^– vegetal masses. The explants were then separated and cultured until siblings reached the mid-gastrula stage, for analysis of dorsal mesodermal markers, and the mid-neurula stage, for the examination of convergence extension movement and the late mesodermal marker, MyoD. (B) The appearance of an equatorial region/vegetal mass co-culture. (C) The appearance of the equatorial regions after separation from the vegetal masses and overnight culture until siblings reached neurula stage 16. (D) Real-time RT-PCR to show the relative levels of expression of organizer genes in sibling equators of those shown in C and D, frozen at the gastrula stage (11, or 16 in last panel). EQ, equator; ß-cat^–/wt bs, ß-catenin^– equator co-cultured with wild-type bases; ß-cat^–/VegT^– bs, ß-catenin^– equator co-cultured with VegT^– bases. In each case, ornithine decarboxylase (ODC) is used as a loading control (data not shown), and each bar is normalized to the level of ODC.