In the pyloric part of stomach lymphoid tissue is present in mucosa of the organ and is represented by:

• single lymphoid nodules #1, #2;
• diffuse clusters of immunocompetent cells in the connective tissue of the lamina propria mucosae;
• lymphocytes, infiltrating the integumentary epithelium of the mucosa.

In the ileum there are cellular elements of lymphoid tissue:

• forming lymphoid nodules #1, #2, #3, localized in submucosa of the organ and collectively forming Peyer's patch;
• infiltrate connective tissue and epithelium of mucosa.

Lymphoid tissue occurs along the entire digestive tube and forms the first line of defense against food and microbial antigens, potentially able to enter the body through the epithelial barriers of the mucous membranes.

For more information, see "Lymphoid tissue associated with the surface. Lymphatic nodes. Spleen"