00:00 / 00:00
Organ system histology
Small intestine histology
0 / 2 complete
The small intestine is the longest portion of the gastrointestinal or GI tract.
It’s approximately 6 meters long in adults and it’s the main site for both digestion and absorption of food in the body.
Although the majority of the small intestine shares similar histological structures, it’s still divided into three main segments.
The duodenum, jejunum, and ileum.
The duodenum connects with the jejunum at the duodenojejunal junction.
The jejunum is approximately 2.5 meters long and will gradually transition to the Ileum, which is the last segment of the small intestine.
Similar to the rest of the GI tract, the wall of the small intestine has 4 main layers: the mucosa, submucosa, muscularis propria, and in the small intestine the outermost layer is a layer of connective tissue called the serosa.
In these images, the serosa is only present in the image of the duodenum.
Even at low magnification, we can see that the finger-like projections or villi that extend into the lumen in both the duodenum and jejunum are very tall and slender when compared to the villi of the ileum are significantly shorter, broader, and their tips are flat in comparison to the duodenum and the jejunum.
Let’s take a closer look at the mucosa of the duodenum.
The small intestine is a long-narrow tube that is part of the digestive system, found between the stomach and the large intestine. It is the primary site of nutrient absorption, where the majority of the breakdown and absorption of food occurs.
The small intestine is composed of four main layers: the mucosa, submucosa, and muscularis propria, and in the small intestine, the outermost layer is a layer of connective tissue called the serosa. The mucosa is the innermost layer and is composed of three layers: the epithelium, the lamina propria, and the muscularis mucosae.
The epithelium is made up of enterocytes, goblet cells, enteroendocrine cells, and Paneth cells. The submucosa contains blood vessels, lymphatic vessels, and nerves. The muscularis externa consists of smooth muscle cells arranged in an inner circular layer and an outer longitudinal layer. The serosa is a thin layer of loose connective tissue that allows the small intestine to move more freely within the abdomen and contains blood vessels, nerves, and lymphatic vessels as well.
Copyright © 2023 Elsevier, its licensors, and contributors. All rights are reserved, including those for text and data mining, AI training, and similar technologies.
Cookies are used by this site.
USMLE® is a joint program of the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners (NBME). COMLEX-USA® is a registered trademark of The National Board of Osteopathic Medical Examiners, Inc. NCLEX-RN® is a registered trademark of the National Council of State Boards of Nursing, Inc. Test names and other trademarks are the property of the respective trademark holders. None of the trademark holders are endorsed by nor affiliated with Osmosis or this website.