Role of Genes in Endoderm-derived Organs.
Pax genes, which encode a family of transcription factors, are essentially required for the formation of several tissues from all germ layers in the mammalian embryo. Specifically, in organogenesis, they are involved in triggering early events of cell differentiation. The differentiation of endoderm-derived endocrine pancreas is mediated through Pax4 and Pax6. In the thyroid gland, Pax8 is essential for the formation of thyroxine-producing follicular cells, also of endodermal origin. The analysis of loss-of-function mutants revealed a common function of Pax genes in organogenesis.