Epithelium This is the innermost layer that comes into direct contact with the lumen. The type of epithelial cells can vary depending on the organ. For example, the gastrointestinal tract features a simple columnar epithelium, while the respiratory tract is lined by a pseudostratified ciliated columnar epithelium.
Lamina Propria Situated beneath the epithelial layer, the lamina propria is a loose connective tissue containing blood vessels, lymphatics, and immune cells. It plays a crucial role in providing nutrients to the epithelium and in immune responses.
Muscularis Mucosae This thin layer of smooth muscle cells aids in the local movement of the mucosa, which facilitates the expulsion of glandular secretions and enhances contact with luminal contents.
