Electron microscopic comparative studies of phagocytic processes between outer segments and latex microspheres in cultured human retinal pigment epithelial cells |
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Authors: | Kiyoshi Akeo Yasuhiko Tanaka Yasuo Uemura Tatsuji Fujiwara |
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Institution: | (1) Department of Ophthalmology, School of Medicine, Keio University, Shinano-machi 35, Shinjuku-ku, 160 Tokyo, Japan;(2) Electron Microscopy Laboratory, Keio University, Shinano-machi 35, Shinjuku-ku, 160 Tokyo, Japan |
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Abstract: | Summary The process of phagocytosis in cultured human retinal pigment epithelium (RPE) cells was observed after more than 2 h of incubation
with human outer segments and latex microspheres. Fingerlike microvilli were attached to outer segments and entwined around
both its ends. The microvilli enveloped the outer segment and cut into the membranous structure, and the same process as that
seen in in vivo shedding was observed. The looplike disk membranes and the whole of the outer segment were ingested into the
cytoplasm and degraded by the lysosome. Latex microspheres were also ingested into the cytoplasm so as to be enveloped in
many fingerlike microvilli. Microfilaments were concentrated in the vicinity of latex microspheres and outer segments, and
latex microspheres were placed between two microtubules. Furthermore, when latex microspheres and outer segments were ingested
into the cytoplasm, the dilated rough endoplasmic reticulum (rER) contained materials of high electron density and attached
ribosomes increased. The rER of the cultured human RPE cells seemed to show a high level of protein synthesis during the phagocytic
process. It was observed that cytoskeletons, such as microfilaments and microtubules, and lysosomes had important functions
in the phagocytic process, and that there were basically no differences among the objects phagocytized by the cultured RPE
cells.
Supported by the Ministry of Education, Japan, through research grant 60771423. |
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Keywords: | human retinal pigment epithelium cell culture phagocytic process outer segments latex microspheres |
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