Absence of lymphatic vessels in the dog dental pulp: an immunohistochemical study

In spite of numerous investigations it has not been precisely determined whether lymphatic vessels are present in the dental pulp of dogs. Therefore, this study attempted a specific immunohistochemical detection of lymphatic endothelium. The canine teeth of 19 healthy beagle dogs were dissected into three segments (apical, intermediate and occlusal). After decalcification, specimens were embedded in paraffin wax and histologic cross-sections were stained immunohistochemically using a reliable antibody (anti-Prox-1) against the homeobox transcription factor Prox-1, which is located within the nucleus of lymphatic endothelium. Anti-Prox-1 reacted positively with canine control tissues (lymph nodes, gingiva, nasal mucosa), but showed no staining in tissue sections of the dental pulp. The dog dental pulp contained no vascular structures lined with lymphatic endothelium. This suggests that drainage of interstitial fluid makes use of other routes, i.e. extravascular pathways.