Myelin basic protein-positive nerve fibres in human Meissner corpuscles.

Myelinated nerve fibres forming sensory corpuscles become amyelinic before entering the corpuscle. Interestingly, in Meissner corpuscles from monkey myelin basic protein (MBP), a specific component of myelin sheath co-localized with neuronal markers. To investigate whether or not this also occurs in human digital Meissner corpuscles, we used single and double immunohistochemistry to detect MBP associated with axonic (protein gene product (PGP) 9.5) or Schwann and Schwann-related cell (S100 protein) markers. We also studied these markers in Pacinian corpuscles. Nerve fibres immunoreactive for MBP were detected in about 25% of the Meissner corpuscles examined; however, MBP never co-localized with PGP 9.5 and MBP occasionally co-localized with S100 protein. MBP-immunoreactive fibres associated with Meissner corpuscles were observed at the periphery of the lamellar cells or within the corpuscle between the lamellar cells. These results describe the distribution of myelinated nerve fibres expressing MBP in human Meissner corpuscles, which is important when studying Meissner corpuscles in cutaneous biopsies used for the diagnosis of peripheral and degenerative neuropathies.

Tissue regeneration in bone defects adjacent to endosseous implants: an experimental pilot study.

Extraction socket defects or alveolar ridge defects may limit or restrict placement of implants. The present study assessed the efficacy of inducing bone formation with demineralized freeze-dried bone (DFDB), osteoinduction with hydroxyapatite (HA), and guided bone regeneration with expanded polytetrafluoroethylene (e-PTFE) in bone defects adjacent to endosseous implants in an animal model. Twenty-four implants were placed in the long bones of 3 pigs. After preparation of 24 cylindric acute defects adjacent to the coronal 5 mm of each implant, 18 of the defects were treated by DFDB, HA, or e-PTFE. The 6 remaining defects healed spontaneously with no treatment (controls). In each pig, one tibia received 4 commercially pure titanium screw implants (3.75 mm x 15 mm), while the contralateral tibia received 4 HA-coated cylindric implants (3.25 mm x 15 mm). Bone formation in response to the 3 treatments and control cases was evaluated using computer-assisted densitometric image analysis. The results showed that a higher density of tissue formed under e-PTFE membranes. A significantly greater increase in bone density was noticed in bone defects treated with an e-PTFE membrane vs DFDB (P = 0.04), in e-PTFE vs control sites (P = 0.04), and in defects treated with HA vs DFDB (P = 0.04) in HA-coated implants. In titanium implants the differences observed were not significant. It was also observed that bone regeneration in defects treated with HA differs with the type of implant used (titanium vs HA-coated implants), but such differences were not significant.