Duodenum is the most proximal portion of the small intestine to the stomach. The mucosa of the duodenum form villi that increases the surface area for absorption. Most unique to the duodenum are the presence of Brunner’s glands in the submucosa that produce and secrete an alkaline-rich mucus to neutralize stomach acid for the digestive enzymes to be functional.
Duodenum. The villi of the mucosa points downward and the pale colored Brunner’s gland are towards the top of the picture. (TM: 100x, picture taken with a Nikon Planapo 10/0.4 on Sony A7ii)Another duodenal specimen showing the Brunner’s gland in the submucosa (bottom of the image). (TM: 100x, picture taken with Nikon Planapo 10/0.4 on Sony A7ii)Villi of the duodenum, showing the simple columnar epithelium that lines the surface. (TM: 400x, picture taken with a Zeiss Planapo 40/1.0 oil on Sony A7ii)
Kit Ng, Ph.D. 