Distribution of the trigeminal sensory nerve fibers of the cat temporomandibular joint (TMJ) was studied using horseradish peroxidase (HRP) anterograde transport. Ten adult male cats weighing 3-4kg were anesthetized and paralyzed, and 10μl of 30% HRP (Type VI) in saline was injected manually into the right exposed trigeminal ganglion using a microsyringe. The cats were sacrificed after 48 hours. The dissected right TMJ capsule and disk were frozen and sectioned serially in either the sagittal or frontal planes at 20μm, and stained with tetramethyl benzidine. The same method was carried out on the left TMJ capsules and disks as controls. The results obtained were as follows :
1) Most of HRP-labeled nerve fibers had undulating courses. All nerve fibers terminated as free nerve endings.
2) No HRP-labeled nerve fibers were observed in the middle of the disk except in one cat.
3) Some of the HRP-labeled nerve fibers observed in subsynovial connective tissue were distributed in the synovial membrane.
4) HRP-labeled nerve fibers were observed in the adventitia of the artery of the TMJ.
5) Most of the HRP-labeled nerve fibers were observed at the boundary area of disk and capsule, and their numbers decreased gradually as the distance from the boundary area increased.
6) More HRP-labeled nerve fibers were observed in the posterior and lateral regions of the TMJ than in the anterior and medial regions.
In this way we were able to determine the trigeminal sensory innervation of the cat TMJ.

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Glutamatergic neurons in the trigeminal complex of the rat were investigated by means of immunohistochemistry using specific antisera against glutamate (GLU) and glutaminase (GLNase), which is considered as a marker of glutamatergic neurons. GLU-like (GLU-LI) and GLNase-like (GLNase-LI) immunoreactive (IR) structures showed similar distributions in the trigeminal ganglion (TG), nucleus of the mesencephalic tract of the trigeminal nerve (Me5), motor trigeminal nucleus (Mo5), principal sensory trigeminal nucleus (Pr5), and nucleus of the spinal tract of the trigeminal nerve (nVsp). IR structures were observed in the marginal and magnocellular layers of the caudal subnucleus of the nVsp (Sp5C).
Injection of a retrograde tracer, fluoro gold (FG), into the ventroposterior medial thalamus (VPM) resulted in labeling a number of cells in the Pr5 and subnucleus interpolaris (Sp5I), some of which were GLNase-LI. A small number of cells double labeled with FG and GLNase-LI was observed in the marginal layer of the Sp5C.
Neurons double labeled with FG and GLNase-LI were observed in Pr5, and Sp5I following injection of FG into the crus 1 (C1), crus 2 (C2), paramedian lobule (PM) and uvula (UV) of the cerebellum. No double-labeled neurons were found in the subnucleus oralis (Sp5O), or Sp5C.
No double-labeled neurons were found in any subdivisions of the trigeminal complex following injections of the two retrograde tracers, fast blue (FB) and FG. The former was injected in the VPM and the latter in the cerebellum.
Neurons double labeled with FB and FG were observed in Pr5, and Sp5I following injections of FB into the C1, C2, and PM, and injections of FG into the UV.
These findings indicate that trigeminal neurons projecting to the thalamus and cerebellum constitute distinct subpopulations, and that some of these neurons are glutamatergic. GLNase-LI neurons in the marginal layer of the Sp5C were shown to project exclusively to the thalamus.

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The purpose of this study was to clarify the effect of pellicle and its lipids on decalcification of the enamel subsurface. A specially designed diffusion chamber with two compartments and a sample port in the central panel was used for measuring the diffusion of hydrogen, calcium and phosphate ions for 150 minutes. Six types of glycoprotein were injected into the sample port and ion diffusion was measured. A fluorescent probe with 8-anilino-1-naphthalene sulfonate was used to determine changes in the hydrophobicity and surface potential of the above glycoprotein membranes.
The permeability of the glycoprotein membrane was inversely proportional to the concentration. In the same solution, an intact glycoprotein membrane retarded ion diffusion more than a delipidated one. It was found that glycoprotein membranes associated with phosphatidylcholine retarded ion diffusion more than membranes associated with cholesterol. Higher hydrophobicity and surface potential was obtained in the phosphatidylcholine than in the cholesterol group.
These findings suggest that the glycoprotein membrane reduces the rate of hydrogen ion diffusion to the tooth surface and the mobility of calcium and phosphate ions from the enamel surface to the fluid environment, and that lipids in the glycoprotein membrane play an important role in protecting the enamel surface against decalcificatlon, creating increased hydrophobicity and surface potential in the membrane.

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Using an electromyograph, I experimentally examined the engagement of the bilateral medial pterygoid muscles (MPt), posterior temporal muscles (Tp) and masseter muscles (Mm) with exertion of horizontal forces during the final phase of closure during mastication. Measurements were carried out using an experimental intraoral apparatus on 5 male subjects with normal jaw function. The myoelectric discharges were measured during mandibular isometric vertical and lateral retrusive contractions at 4 different force levels (1/4, 1/2, 3/4 and maximum) at 4 different jaw positions (habitual closing position and three eccentric positions).
The results were as follows :
1. EMG activities increased significantly in the ipsilateral MPt and contralateral Tp during lateral retrusive contraction for each of the 4 forces and each of the 4 positions.
2. The mean EMG amplitudes for the ipsilateral MPt during lateral retrusive contraction were lower than those during vertical contraction, although there was no statistical difference between the two. This implies the ipsilateral MPt strongly engages in both vertical and lateral retrusive occlusion.
3. Lateral retrusive forces were always associated with vertical force.
From these findings it was concluded that the ipsilateral medial pterygoid muscle plays an important role in horizontal force exertion during the final phase of closure during mastication.

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Breeding and reproductive records were kept for SAM-R/1 and SAM-P/8, and their behavioral characteristics were investigated. The animals were cared for under conventional conditions in our Experimental Animal Facilities.
The results obtained were as follows.
1. We bred the two inbred sublines to the F-4 generation.
2. We found no significant difference in the gestation periods or litter sizes.
3. Differences were found in hair loss and lordokyphosis of the spine by visual inspection, palpation and soft X-rays.
4. The life span of the SAM-P/8//ODU was the shorter.
5. Step down latency, as measured by the step-down passive avoidance response, was shorter at 20 weeks in the SAM-P/8//ODU.
These results indicate that mice of the two sublines, SAM-R/1//ODU and SAM-P/8//ODU, keep their essential characteristics and can be used as stable murine models.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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