Liver and pancreas: Mechanisms of development and size control

The Gastrointestinal (GI) system is primarily comprised of the liver, pancreas and luminal tract. Together, these organs play a critical role in nutrient homeostasis, synthetic function and toxin removal (Table 1). The liver is mainly responsible for sustaining serum protein and metabolite concentrations, drug metabolism, detoxification and bile production. The endocrine pancreas works to tightly control serum glucose metabolism while it’s exocrine portion aides in digestion of nutrients. The GI tract functions to digest food, extract nutrients and dispose of waste. Despite their varied functions, these organs share a common embryological origin, being derived primarily from the endoderm with contributions from mesoderm and ectoderm germ layers (Table 2). Advances over the past 1-2 decades have given us insight into the genes, transcription factors and pathways involved in the patterning, morphogenesis and differentiation of gut endoderm.