midguts

Midguts (plural) refers to the midgut, a region of the digestive tract between the foregut and hindgut. In humans and many vertebrates, the midgut extends from the distal portion of the duodenum through the proximal two-thirds of the transverse colon and is supplied mainly by the superior mesenteric artery. In insects and some invertebrates, the midgut is a distinct organ between the foregut and hindgut that serves as the central site of digestion and nutrient absorption.

In vertebrates, the midgut includes most of the small intestine and a portion of the large intestine. Its mucosa bears villi and microvilli that maximize absorption, while crypts renew the epithelium. Digestive enzymes and secretions from the pancreas and liver enter here to break down nutrients, which are absorbed into the bloodstream and lymphatics. The midgut hosts much of the gut microbiota.

Developmentally, the midgut arises from the midregion of the primitive gut tube. It elongates, herniates into the umbilical cord, rotates about 270 degrees around the axis of the superior mesenteric artery, and returns to the abdomen. Abnormal rotation or fixation can cause malrotation and midgut volvulus, with potential obstruction or ischemia.

In insects, the midgut is the principal digestive and absorptive organ, lined by a simple epithelium and often protected by a peritrophic matrix that encases the food. Digestion occurs in the lumen and nutrients are absorbed by epithelial cells; intestinal stem cells renew the lining. Across taxa, midguts denote central gut regions that support digestion and nutrient uptake.