Abstract
The fine distribution of the intramural lymphatics at the ileocecal junction of the monkey intestine, especially in the lamina propria of the ileocecal valve, was examined by light and electron microscopy using enzyme-histochemical staining. The distinction between the lymphatics and the blood vessels was made by light microscopy on cold glycol methacrylate resin (JB-4) sections using 5'-nucleotidase (5'-Nase)-alkaline phosphatase (ALPase) double staining. The lymphatics were found to show strong 5'-Nase activity and to comprise irregularly shaped vessels or spaces. The central lymphatic vessels (central lacteals) in low villi were seen to lie deep within the ALPase-positive subepithelial capillary network. In the ileum side of the ileocecal junction, the 5'-Nase-positive lymphatics were seen both in the superficial layer and the deep layer of the lamina propria. On the contrary, in the cecum side the mucosal lymphatics were less numerous in the superficial layer and were distributed mainly in the deep layer near the lamina muscularis mucosae. These lymphatics ran through the lamina muscularis and merged into the lymphatic network in the submucosa. The submucosal lymphatics communicated with each other at the ileocecal junction and formed a well-developed network. Collecting lymphatics with valves were also seen near the tunica muscularis (sphincter muscle) in the deep submucosa. These lymphatics traversed the muscle layer and drained into the subserosal lymphatics.
