Osmosis video - Development of the gastrointestinal system

The gastrointestinal system starts to develop around week 3 of prenatal life. The earliest indication of gastrointestinal development is a thickening in the midline of the embryo that will become the gut tube. This thickening begins to form a groove along its length, and by week 5 of development this groove has divided into 3 sections: foregut, midgut, and hindgut. Each section will give rise to different parts of the gastrointestinal system.

The gastrointestinal system develops from all three germ layers (ectoderm, mesoderm, and endoderm). The ectoderm gives rise to the enteric nervous system; mesoderm gives rise to the connective tissue, including the wall of the gut tube and the smooth muscle, whereas the endoderm gives rise to the epithelial lining of the digestive tract, as well as to all of the associated glands and organs such as the liver, gallbladder, and the pancreas.