ABSTRACT
The endoderm is the inner most germ layer of the vertebrate embryo that gives rise to the epithelial lining and organs of the respiratory and digestive systems. Over the past 50 years, studies using Xenopus have provided many fundamental contributions to our knowledge of vertebrate organogenesis, revealing critical information about the basic biological mechanisms that underlie normal human health and disease. An amphibian tetrapod, Xenopus bridges the gap between more costly mammalian models and the evolutionarily more distant zebrafish model. In this chapter, we summarize the current understanding of Xenopus endoderm organogenesis in four major sections: (1) a temporal overview of Xenopus endoderm organogenesis, (2) endoderm germ layer specification, (3) progressive patterning of the endoderm gut tube, and (4) organ fate induction. In each section, we highlight conserved molecular mechanisms, pointing out both historical and recent contributions of Xenopus research. We also emphasize how the use of emerging technologies in Xenopus continues to inform our molecular understanding of human congenital birth defects and disease.
