• Absorptive cells, which produce d

• Absorptive cells, which produce digestive enzymes and absorb nutrients from digested food. • Goblet cells, which produce protective mucus that lubricates the surface and protects it from mechanical damage. • Granular cells,which protect the intestinal epithelium from bacteria. • Endocrine cells, which produce peptide hormones that regulate secretion and motility in the gastrointestinal tract, liver and pancreas.
Two types of gland are present in the duodenum. At the base of the villi are tubular invaginations that reach almost to the muscularis layer; these are known as the intestinal crypts or crypts of Lieberkuhn. The submucosa of the duodenum contains coiled compound tubular mucous glands, known as the glands of Brunner, which secrete an alkaline fluid rich in mucus. These are more numerous in the proximal region of the duodenum.