A thin layer of loose connective tissue which lies beneath the epithelium and together with the epithelium constitutes the mucosa[WP]. The lamina propria contains capillaries and a central lacteal (lymph vessel) in the small intestine, as well as lymphoid tissue. Lamina propria also contains glands with the ducts opening on to the mucosal epithelium, that secrete mucus and serous secretions. [ http://en.wikipedia.org/wiki/Lamina_propria ]