Intestinal cross-section
The microscopic structure of the intestinal wall follows the same basic pattern in all sections of the intestine. The innermost layer of the intestinal wall is the intestinal mucosa. The mucosa forms villi or indentations called crypts. Villi are formed in the small intestine, while crypts are typical of the mucosa in the large intestine. The mucosa consists of several very thin layers: a thin muscular layer, followed by a connective tissue layer, the submucosa. Very fine blood vessels, lymphatic vessels, and nerve branches terminate in the submucosa. The next layer is the muscular layer, also known as the muscularis. The muscularis consists of transverse and longitudinal muscle fibers. This muscular arrangement allows the Intestine to move freely. The intestinal wall contracts both lengthwise and crosswise. This allows the food pulp to be transported further. The outermost layer of the intestine is called the serosa or adventitia and consists of thin connective tissue. In some sections of the intestine, the serosa is formed by the peritoneum, the lining of the abdomen.
The layers of a natural casing can be seen in cross-section from the outside in. The outermost layer is the so-called subcutaneous fat, followed by the serosa (epidermis), the submucosa, the muscle layers, and finally the mucous membrane with the intestinal villi.
The outer layer of fat is the layer of fat around the internal organs, including the intestines.
The serosa is a layer of skin that covers the intestines.
The submucosa is a coarse-fibered, vascular connective tissue sheath and the lower or inner part of the serosa.
The muscle layer is processed into the actual natural casing. It consists of a longitudinal and transverse fiber layer.
The mucous membrane consists of intestinal villi and intestinal glands and is removed during mucus production.
