Patches of lymphoid nodules are present in '''[[Peyer's Patches - Anatomy & Physiology|Peyer's Patches]]'''. They are most abundant in the '''[[Duodenum - Anatomy & Physiology|duodenum]]'''. There are no mesenteric lymph nodes. | Patches of lymphoid nodules are present in '''[[Peyer's Patches - Anatomy & Physiology|Peyer's Patches]]'''. They are most abundant in the '''[[Duodenum - Anatomy & Physiology|duodenum]]'''. There are no mesenteric lymph nodes. |