Figure 3.

Dramatic shift in response to Wnt signaling in early Xenopus embryogenesis. Early Xenopus development is regulated by maternal gene products. Maternal Wnt signaling regulates dorsal axis establishment. After the MBT and the onset of zygotic transcription, Wnt signaling regulates essentially the opposite, ventral development or more precisely ventrolateral mesoderm development. Responses to maternal and to early zygotic Wnt signaling are mediated by essentially the same β‐catenin‐dependent signal transduction mechanism depicted in Figure 1