Ultrastructure of lymphatic capillaries in the human dental pulp.

Occlusal intradentinal cavities, prepared in normal human premolars and third molars to be extracted for orthodontic reasons, were filled for 7 to 11 days with gutta percha. A superficial pulpitis with localized small abscesses developed in the pulp chamber. Under local anesthesia, 0.2 to 0.3 cc of sterile colloidal carbon was injected in the pulp horn and the teeth were extracted 1 to 3 h later. Lymphatic capillaries could thus be identified in the pulpal tissues. They were characterized by a thin endothelium with occasional large intercellular clefts, absence or incompleteness of basement membrane, absence of pericytes, absence of luminal red blood cells, and presence of a filamentous material between the endothelium and the surrounding collagen fibrils. Moreover, some structural variations were observed.