| Project/Area Number |
02454416
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Morphological basic dentistry
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| Research Institution | Osaka University (1991)
Kyushu University (1990) |
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Principal Investigator |
KURISU Kojiro Osaka University, Faculty of Dentistry, Professor, 歯学部, 教授 (50028346)
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| Co-Investigator(Kenkyū-buntansha) |
NAGATA Kengo Kyushu University, Faculty of Dentistry, Assistant, 歯学部, 助手 (90189134)
MATSUO Saburo Osaka University, Faculty of Dentistry, Instructor, 歯学部, 講師 (30144497)
WAKISAKA Satoshi Osaka University, Faculty of Dentistry, Assistant Prof., 歯学部, 助教授 (40158598)
KUKITA Toshio Kyushu University, Faculty of Dentistry, Assistant Prof. (70150464)
OHSAKI Yasuyoshi Kyushu University, Faculty of Dentistry, Assistant (00193566)
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| Project Period (FY) |
1990 – 1991
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| Project Status |
Completed (Fiscal Year 1991)
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| Budget Amount *help |
¥7,000,000 (Direct Cost: ¥7,000,000)
Fiscal Year 1991: ¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1990: ¥5,000,000 (Direct Cost: ¥5,000,000)
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| Keywords | ameloblast / odontoblast / Tooth Germ / immunohistochemistry / Monoclonal Antibody / rat / 発生 / 分化 |
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| Research Abstract |
In order to examine the synthesis and secretion of enamel protein by ameloblasts in their early stages of development, immunohistochemical localization was carried out at light and electron microscopic levels using a monoclonal antibody produced in a preliminary experiment. Materials used were tooth germs of mandibular first molars of rats at 1-5 days after birth.
Immunoblotting analysis after two-dimensional electrophoresis revealed that antigen molecules of the monoclonal antibody used were amelogenin of 26 kDa(PI, 5-6). An immmunohistochemical examination using this monoclonal antibody demonstrated that the preameloblasts in their early stages of differentiation both synthesized amelogenin and secreted through a classical merocrine secretory pathway. In some preameloblasts as well as ameloblasts we observed the distended cisternae of rER which demonstrated heterogenous immunolabelling. The immunolabellings were also detected in the predentin as well as the intercellular spaces of odo
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ntoblasts and dental papilla cells which indicated penetration of amelogenin from the ameloblast layer to the dental papilla. The presence of coated pits at the plasma membrane of odontoblasts in close proximity to enamel protein along with the immunolabelling of lysosome of the odontoblasts suggest the phagocytosis of the enamel protein into the odontoblasts. These observations indicate that the penetration of enamel protein toward dental papilla including odontoblasts plays a role in the interaction between ameloblasts and odontoblasts.
The enamel-free area of 1-4 day-old rat mandibular first molars were investigated using the monoclonal antibody En3 against rat amelogenin at light and electron microscopic levels in order to clarify whether the enamel-free area is virtually devoid of enamel. Although the presecretory ameloblast-like cells(PALCS)were not polarized, almost continuous immunofluorescence for amelogenin was detected at the interface between PALCs and dentin. Immunoelectron microscopic examination also revealed the positive labelling in the Golgi apparatus and secretory vesicles in PALCs and in the layer of amorphous materials between PALCs and dentin. These results suggest that PALCs at enamel-free area synthesize and secrete amelogenin the penetration of which toward the dental pulp might play a role in the interaction between PALCs and odontoblasts in the enamel-free area and/or the initiation of mineralization of predentin. Less
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