Postnatal development of the juxtaoral organ as a muscle receptor of masticatory muscles
| Project/Area Number |
07838038
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 時限 |
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| Research Field |
咀嚼
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| Research Institution | TOKYO DENTAL COLLEGE |
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Principal Investigator |
YAMAMOTO Tetsu Tokyo Dental College, Department of Physiology ; Lecturer, 歯学部, 講師 (90096511)
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| Co-Investigator(Kenkyū-buntansha) |
OZONO Satoru Kanagawa Dental College, Department of Pathology ; Lecturer, 歯学部, 講師 (40084785)
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| Project Period (FY) |
1995 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1996: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1995: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Keywords | juxtaoral organ / postnatal development / sensory nerve endings / buccal stretch receptor / Buccal stretch receptor |
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| Research Abstract |
The developmental relationship between function and structure of the juxtaoral organ in rats was investigated using the electrophysiological and morphological techniques. For functional analysis, sustained discharges in response to ramp-and-hold stretches were recorded from the juxtaoral organs isolated from Wistar rats aged 10 days to 10 weeks. All sensory units of the animals of 10-12 days old showed nothing but brief discharges at the end of the dynamic phase of stretch. The threshold amplitude of stretch of the juxtaoral organ for a sustained discharge fell significantly between 10 days and 3 weeks reaching adult values at 5 weeks of age. On the other hand, the static sensitivity increased conspicuously between 2 and 4 weeks after birth.
Electron microscopic examination revealed a conspicuous expansion of the capsular space caused by completion of the outer capsule between 2 and 4 weeks after birth. Moreover, between 1 and 4 weeks of age, age-dependent increases were observed in the number of preterminal branches in a sensory unit, in the size of the varicose-like swellings along the terminal axon, and in the density of collagen and elastic fibers around the core structure. Immunohistochemical investigation showed that the capsular space between inner and outer capsules contained hyaluronate ions. When hyaluronate ions in the capsular space were removed with a treatment of hyaluronidase, the sustained discharge of the organ was disappeared. The sustained discharge was appeared again by addition of 6 mM-KCl in the bathing solution.
These results suggested that the negatively charged hyaluronate ions in the capsular space of the juxtaoral organ contributed to the depolarization of sensory terminal membranes resulting in an increase in the excitability of this organ.
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Report
(3 results)
Research Products
(6 results)
