Immunohistochemical identification of lymphatic vessels in the periodontium of equine cheek teeth.

This research examines the distribution of lymphatic vessels in the periodontium (tissues that surround and support the teeth) of horse cheek teeth. The findings suggest that these vessels have two main pathways for draining lymph fluid: one via the gums to the mandibular lymph nodes and the other via the bone marrow of the jaws to the retropharyngeal lymph nodes.

Methodology

• For this research, the scientists used cheek teeth from six horses aged between 3 and 23 years.
• They sliced tissue sections from four different horizontal layers along the tooth’s long axis.
• The tissue samples underwent a process known as immunoreaction using anti-Prox1. This treatment helped differentiate lymphatic endothelium, which forms the lining of lymphatic vessels, from blood vascular endothelium, the lining of blood vessels.

Findings

• Lymphatic vessels were identified in all periodontal tissues, excluding the dental cementum — the surface layer of the tooth’s root.
• They discovered that these vessels were most densely found in the gum tissue in comparison to other periodontium sections.
• There was a consistency in the samples from all the horses – lymphatic capillaries were particularly present in the gum and directly below the gum.
• Of these areas, the gums and the spongy bone marrow tissue of the jaws showed the highest incidence of lymphatic vessels.

Conclusion

• The research concluded that the contrast in the distribution of lymphatic capillaries in the periodontium of the maxillary (upper jaw) and mandibular (lower jaw) cheek teeth implies two complementary lymphatic drainage pathways.
• One pathway involves superficial lymph drainage via the gums that empty into the mandibular lymph nodes.
• The other is a deep lymph drainage conduit via the spongy tissue of the mandibular and maxillary bones, which empty into the mandibular and retropharyngeal (located behind the pharynx in the neck) lymph nodes respectively.