Small intestinal villi refer to many villous protrusions on a large number of annular wrinkles on the inner surface of the small intestinal wall. Small intestinal villi grow on the small intestine. The function of small intestinal villi is to increase the absorption area of small intestine. It is a leaf-like structure formed by the lamina propria and epithelium protruding to the intestinal cavity, and the mass-like structure free in the intestinal cavity is the cross section of villi.

Small intestinal gland is located in the lamina propria and opens at the basal part between adjacent villi. It is mainly composed of columnar cells, goblet cells and panet Shi cells. The number of columnar cells is the largest, and the striation margin is not obvious, and only intestinal activating enzymes can be secreted. Paneth cell is located at the bottom of gland, with pyramidal cells and coarse eosinophilic granules at the top of cytoplasm. Paneth cell can secrete lysozyme. Paneth cell is not contained in the colon and intestinal glands.

Compared with the small intestine gland, the lumen in the center of villi is larger, and the central mammary duct, which is composed of a single layer of endothelium, is lymphatic capillary. There are scattered smooth muscle bundles around the duct. The wall of small intestine villi is only a small layer thick. The villi of the small intestine are covered with reticular microvessels. Small intestine is the main place for digestion and absorption. Intestinal villous epithelial cells absorb amino acids, glucose and inorganic salts from the digestive tract into the blood. If this part is damaged, it will affect the absorption of the above nutrients, and soluble sugar and other nutrients can be detected in feces.