Biology of the pancreas before birth

The pancreas is an endocrine and exocrine organ that is essential for life ex utero. Hormones secreted into the circulation play a central role in mai ntaining homeostasis of energy and protein metabolism. Enzymes secreted int o the gastrointestinal lumen are required for the hydrolysis of food macrom olecules to allow nutrient absorption. In the fetus, nutrients are transfer red across the placenta and not via the fetal gastrointestinal tract, and n utrient flow is relatively constant. Does this mean that the pancreas has l ittle to do in utero? This review describes the main features of pancreatic development before birth in some large domestic species (pig, sheep, cow). A series of experimental studies on fetuses suggest that function bf the e ndocrine pancreas is required for fetal nutrition and growth. However, both the endocrine and exocrine entities of the pancreas are relatively immatur e in structure and function, even in late gestation, and mature function is not present until several weeks after birth. Pancreatic development seems to be particularly rapid around the time of birth, and factors such as the fetal glucocorticoid levels, the events leading to birth, and the first int ake of enteral milk stimulate these maturational changes.