1991 Fiscal Year Final Research Report Summary
A Morphological and Functional Study of Choroidal Melanocytes
| Project/Area Number |
63440066
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
Ophthalmology
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| Research Institution | Tokyo Medical and Dental University |
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Principal Investigator |
TOKORO Takashi Tokyo Medical and Dental University, Dept. of Ophthalmology, Professor, 医学部・眼科学教室, 教授 (20013865)
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| Co-Investigator(Kenkyū-buntansha) |
AKAZAWA Yoshihiko Tokyo Medical and Dental University, Dept. of Ophthalmology, Clinical fellow, 医学部・眼科学教室, 助手 (70159317)
HIRAI Keiji Tokyo Medcial and Dental University, Medical Research Institute, Dept. of Autono, 難活疾患研究所・自律生理部門, 助教授 (70156628)
KATAYAMA Yoshifumi Tokyo Medical and Dental Universtiy, Medical Research Institute, Dept. of Autono, 難活疾患研究所・自律生理部門, 教授 (20014144)
FUNATA Midori Tokyo Medical and Dental University, Dpet. of Ophthalmology, Lecturer, 医学部・眼科学教室, 講師 (10143554)
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| Project Period (FY) |
1988 – 1991
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| Keywords | Choroidal melanocyte / Choroidal fibroblast / Suprachoroid / VIP / Interfibroblastic space / Fura-2 / Gap junction / Ca^<2+>-uptake |
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| Research Abstract |
This study was performed to clarify the morphology and function of the choroidal melanocytes. Eyes of macaque monkeys, pigmented rabbits and cats were used for the morphological study. In the suprachoroidea, the fibroblasts had long thin cytoplasmic processes and were in contact with neighboring cells by intercellular junctions, thus forming a network.
Melanocytes were wedged between the thin processes of fibroblasts, and surrounded by collagen fibers and elastic fibers. In some areas, there were interfibroblastic spaces, which were devoid of fiber elements and filled with amorphous substances. When the tracers such as a suspension of activated carbon were injected into the anterior chamber, these tracers were detected in the interfibroblastic spaces at the suprachoroid. So, these spaces may function as the lymphatic route. Furthermore, we examined VIP-positive nerve fiber in the choroid of human enucleated eye by electron microscopical immunohistochemstry. Although VIP-positive nerve fibers were observed in the suprachoroid and inner scleral layers near choroidal melanocytes, no direct contact between VIP-positive nerve fibers and melanocytes could be found.
In addition, electron microscopy revealed the gap junction between choroidal melanocytes and physiological methods demonstrated dye coupling and electrical coupling between choroidal melanocytes in rabbit's eyes. Thus it can be hypothesized that a group of choroidal melanocytes may function as a unit by exchanging ions and bioactive substances through their intercellular communication system, the gap junction. Furthermore, we investigated the suprachoroid uptake of extracellular calcium ions by using fura-2 and found that the intercellular calcium ions concentration was significantly increased by ATP superfusion. So, one of the functions of melanocytes and fibroblasts may be to regulate the extracellular fluid in the choroid.
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