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tropicalis, the Western clawed frog, are useful animal models for developmental studies. Historically, the ease of experimental em-bryonic manipulation and the rapid maturation of the free-living embryo attracted scientists interested in vertebrate development to these frogs. More recently, studies have taken advantage of the conservation across phyla of the development of organ systems, especially the development of the heart. Aberrations in cardiac development and function can be characterized through a variety of elegant techniques in the embryo to give insight into the ori-gins of human disease.3,5,13,15,19 The Xenopus heart has 3 chambers, with right and left atria, a common atrioventricular valve, and a single ventricle that gives rise to the truncus arteriosus.10 Xenopus studies traditionally use X. laevis; however, work has expanded into X. tropicalis as the field has progressed; although smaller than X. laevis, X. tropicalis matures more quickly and has a fully se