Xenopus is an established and powerful model system for the study of Wnt signaling in vertebrates. Above all, the relatively large size of the embryos enables microinjection experiments, which have led to key discoveries not only about the functional role of Wnt signaling in vertebrate embryos, but also about the molecular mechanisms of Wnt signaling in vertebrate cells. A major advantage of the Xenopus model is the ability to obtain large numbers of embryos, which develop relatively rapidly and which can be studied in natural separation from sentient adult parental animals. In order to obtain Xenopus embryos, ovulation in females is induced with a simple hormone injection, the eggs collected and fertilized with sperm from males. The Xenopus model system has been further strengthened by recent advances such as morpholino technology and efficient transgenic methods, as well as the development of Xenopus tropicalis as a diploid genetic model system with a shorter generation time and a genome similar to higher vertebrates.