| Research Abstract |
1. Postnatal development of periodontal Ruffini endings was investigated in rat incisors by immunoelectron microscopy using PGP 9.5-antibody. The immunoelectron microscopic findings suggested that mechanical stimuli due to tooth eruption and occlusal forces might be a prerequisite for the final differentiation and maturation of the periodontal Ruffini endings.
2. In an experimental model, artificial occlusal forces easily induced the forms of the periodontal Ruffini endings, but the damaged terminal formation recovered to normal morphology after complement of tissue repair. Furthermore, thin nerve fibers, beaded in appearance, occurred in the period when tissue remodeling took place.
3. In an experimental tooth model, the expression pattern of growth associated protein-43 (GAP-43), a key molecule in neural plasticity, was altered in the axon terminals of the periodontal Ruffini endings. On day 3-5 after tooth movement, immunoreactivity for GAP-43 was temporally found in the axon terminals which lack immunoreaction in physiological conditions.
4. The periodontal Ruffini endings exhibited immunoreactivities for calbindin D28k and calretinin, both of which play important roles in mechanotransduction.
5. In the nerve injury model to crush inferior alveolar nerves, immunoelectron microscopy revealed the temporal expression of neuropeptide Y,which is usually co-localized in noradrenalin in the sympathetic nervous system, in the axon terminals of the periodontal Ruffini endings.
6. Scanning electron microscopy using a chemical maceration technique revealed a three-dimensional structure of the periodontal Ruffini endings. Furthermore, they developed Schwann cell processes which serve as an anchor of these endings in the periodontal ligament.
To obtain these findings mentioned above, the ultramicrotome, which was purchased by grant #08457478, was utilized throughout this research project.
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