Enzyme-histochemical demonstration of the intramural lymphatic network in the monkey jejunum

The structural organization of the intramural lymphatic networks in the jejunum of the Japanese monkey (Macaca fuscata) was studied by an enzyme-histochemical method using whole-mount preparations of tissue layers. A distinction between the lymphatics and the blood vessels was made by light microscopy using 5'-nucleotidase (5'-Nase)-alkaline phosphatase (ALPase) double staining. In each tissue specimen, the reaction product for 5'-Nase activity was localized in the lymphatic vessels, whereas that for ALPase activity was restricted to blood vessels. The mucosal layer exhibited an irregular network of tubular lymphatics connecting to the central lymphatics in the villi. The submucosal layer revealed a horizontal mesh-like network consisting of tubulo-saccular lymphatics. A dense maze-like network of lymphatics was distributed throughout the myenteric layer. The lymphatic networks were independent of the blood vessels. The present results indicate the usefulness of the enzyme-histochemistry of whole-mount preparations of the laminar layers for demonstration of the structure and distribution of the lymphatic system in the intestinal wall.