We examined the normal intraneural vascularisation of the infraorbital nerve from the infraorbital foramen to the peripheral vibrissae to know a normal intraneural vascularisation in a peripheral pure sensory nerve. Indian ink was injected into the heart of the mouse for observation of vascular architecture in the infraorbital nerve. Three-dimensional images of blood vessels in the infraorbital nerve were then reconstructed using 3D visualization software.Optical microscopic observation of the peripheral section of the normal mouse infraorbital nerve (near mouse vibrissae) revealed fascicles of nerve fibers (10-60 µm in diameter) covered with perineurium, with one blood vessel normally present within the fascicle. Optical microscopic observation of the cross-section of normal mouse infraorbital nerve near the infraorbital foramen revealed nerve fiber fascicles (about 150 µm in diameter) covered with epineurium extending from proximal to peripheral areas, increasing in number as they branched. In the nerve fascicle surrounded by the perineurium near the infraorbital foramen, a few blood vessels were distributed. As the nerve fascicle branched and extended, the blood vessels also branched, providing one blood vessel in each nerve fascicle. There were multiple blood vessels in between the epineurium and perineurium. The blood vessels in nerve fascicles consisted of thin branches communicating with blood vessels outside of the perineurium. Nerve fascicles were surrounded by networks of blood vessels communicating with capillaries, arteriolae and venulae. Some blood vessels showed chain-like distribution in nerve fascicles. In the peripheral part of the infraorbital nerve, the blood vessel in the nerve fascicle exited before the nerve entered a vibrissa. The blood vessel goes out of the nerve to this point that enters the vibrissa.

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In order to model the vascularization stage of periodontal recovery, platelet-rich plasma (PRP) was applied to the sockets of the beagle dog's dentition. Microvascular resin injection was performed 14, 30, and 90 days later and examined by light and scanning electron microscopy to investigate the relationship between bone formation and vascular changes. Bone formation ratios were measured from the scanning electron microscopic images. Fourteen days after the operation, newly formed blood vessels filled the untreated sockets, except for the center portion. These blood vessels had regenerated along the pre-existing bone wall of the socket. In the sockets treated with PRP, however, the sockets were filled with newly formed bone, and regenerated blood vessels were surrounded by new bone. Thirty days after the operation, the insides of the sockets were filled with newly formed porous bone in both groups. In untreated sockets, porous new bone formation was observed along the blood vessels, but in sockets treated with PRP, bone trabecula and blood vessels were arranged in the porous bone. Ninety days after the operation, both treated and untreated sockets contained regenerated normal bone tissue, with bone marrow reproduced along the trabeculae and vascular networks observed. However, the bone formation ratios of the PRP-treated sockets were significantly higher than the untreated sockets after 14 and 30 days. At 90 days, nearly identical bone formation was measured in both groups. Taken together, these observations suggest that PRP application to the extraction sockets advanced bone regeneration and promoted regeneration of the blood vessels.

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Introduction: Remodeling of tissues frequently occurs in the periodontal ligament during orthodontic tooth movement, including various changes in the vascular system. Although studies have investigated lymphatic vessels in the periodontal tissues, only a few studies have observed lymphatic vessels in the periodontal ligament, leaving many unclear aspects.
Materials and Methods : Using mice (PN-0, 7 and 14 days old) with unerupted mandibular first molars, lymphatic distribution and the existence of lymphatic vessels in the periodontal tissues including the periodontal ligament were immunohistochemically (LYVE-1) observed.
Results: Lymphatic vessels were observed beneath the oral epithelium, beneath the epithelium of the attached gingiva and inside the mandibular canal. Some lymphatic vessels beneath the epithelium of the attached gingiva were present along the alveolus. Although LYVE-1 positive structures distributed irregularly at each age in the areas of periodontal ligament at the future sites of crown formation, root formation and root apical region of root formation, no lymphatic vessels were identified.
Discussion: In the periodontal ligament of adult mice, it was supposed that lymphatic vessels in the periodontal ligament except the apex of root were not distributed from initial stage, and lymphatic vessels were observed near the apex in adult mice was distributed during the apex of root completion stage. This might be connected to the presence of the Hertwig's epithelial sheath.

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