Hisao Ajima

Immunocytochemical demonstration of laminin in the synovial lining layer of the rat temporomandibular joint.

This immunocytochemical study describes the distribution of laminin in the synovial lining of the rat temporomandibular joint. Laminin immunostaining was present around some synovial lining cells and blood vessels. Ultrastructurally, immunoreactive products for laminin were deposited around cells with a well-developed rough endoplasmic reticulum and secretory granules, suggesting that they were type B synovial lining cells. The localization of laminin immunoreactivity was not uniform around the cell membrane, the most intense immunoreaction being present on the basal aspect membrane as is seen in the basement membrane of epithelia. In contrast, macrophage-like synovial lining type A cells did not show laminin immunoreactivity. This different immunostaining pattern suggests that laminin acts as an adhesion molecule for the type B cells in their epithelial-like arrangement.

Expression of 25 kDa heat shock protein by synovial type B cells of the mouse temporomandibular joint

Earlier studies have demonstrated immunoreactivity for heat shock protein 25 (Hsp25) in type B synovial lining cells of the rat temporomandibular joint, and also the presence of characteristic cytoplasmic processes in these cells, but it is unclear whether or not the type B cells in other animals possess such elaborate cytoplasmic projections and as there is as yet no evidence for the synthesis of this protein by these cells. For these reasons, the expression of Hsp25 was investigated in the synovial membrane of the mouse temporomandibular joint by immunocytochemistry and by in situ hybridization using a specific cRNA probe. Intense immunoreaction for Hsp25 was found in the cytoplasm of certain synovial lining cells that were identified as type B by immunoelectron-microscopy. These Hsp25-positive cells had slender cytoplasmic processes, either projecting towards or covering the synovial surface. Morphological differences between cytoplasmic processes seemed to depend on the location of the type B cell bodies. In situ hybridization showed intense signals for Hsp25 mRNA in the synovial lining cells, suggesting that the type B cells produce, rather than resorb, Hsp25. These findings indicate that Hsp25 is a useful marker for the identification of the synovial type B cells in the temporomandibular joint. It is further hypothesized that Hsp25 in type B cells is involved in maintaining their specific profile and epithelial-like arrangement, and in protecting against mechanical stress.

Delayed Expression of Calbindin D28k during Regeneration of the Periodontal Ruffini Endings of the Rat Incisor following Injury to the Inferior Alveolar Nerve

Expression of calbindin D28k (CB)-like immunoreactivity (-LI) was compared with that of protein gene product 9.5 (PGP 9.5), a general neuronal marker, in the periodontal ligament of the rat lower incisor following resection of the inferior alveolar nerve (IAN). In normal animals, the periodontal nerve fibers showing PGP 9.5-LI formed either Ruffini endings with expanded arborization or thin free nerve endings in the alveolar half of the ligament. Thick CB-like immunoreactive (-IR) nerve fibers terminated in a dendritic fashion in the same region, but thin CB-IR nerve fibers were rarely detected. During the 3 days following resection of the IAN, most of the PGP 9.5-IR and all CB-IR nerve fibers disappeared. Regenerated PGP 9.5-IR nerve fibers appeared around 7 days after resection, in contrast to the very small number of regenerated CB-IR nerve fibers. Around 21–28 days following resection, the number and terminal morphology of regenerated PGP 9.5-IR nerve fibers were comparable to those observed in normal animals, but the number of regenerated CB-IR nerve fibers was still smaller. The terminal morphologies of these regenerated CB-IR nerve fibers showed less expansion compared with normal animals at these post-injured periods. The number of regenerated CB-IR nerve fibers increased gradually to return to normal by 56 days following injury. The delayed expression of CB in the regenerated periodontal Ruffini endings suggests that the functional recovery of periodontal Ruffini endings occurred after the regeneration of periodontal Ruffini endings had been completed.

Placement of mandibular nerve block using computed tomography to locate the foramen ovale in a patient with severe dislocation after segmental mandiblectomy

Operations to the face and skull can obscure the landmarks that are required to locate the position of the foramen ovale. We describe the use of three-dimensional computed tomography (3D-CT) to guide the approach to the foramen ovale to block the mandibular nerve in a patient with a mandibular deformity that had been caused by segmental mandiblectomy. Successful blockage of the mandibular nerve controlled the pain, contributed to the relief of physical and mental stress, and avoided the side effects of analgesics and pain from inserting the blocking needle.