Fine structure and distribution of lymphatic vessels in the human dental pulp: a study using an enzyme-histochemical method.

The existence of lymphatic vessels in the human dental pulp and their distribution were established by light and electron microscopy using an enzyme-histochemical method. The distinction between lymphatic and blood vessels was made by light microscopy on cryostat sections of undecalcified and decalcified teeth using 5'-nucleotidase(5'-Nase)-alkaline phosphatase double staining. On the tissue surface, 5'-Nase-positive lymphatic vessels were highlighted with good contrast and resolution by backscattered electron imaging using scanning electron microscopy. By transmission electron microscopy, dense granular precipitations resulting from the 5'-Nase reaction were seen on the luminal surface of the lymphatic endothelial cells as well as in the area at the basal side, but were absent in the blood vessels. These lymphatic vessels were more numerous in the central part than in the peripheral odontoblastic layer.