Finger-like projections of plasma membrane in the most senescent fiber cells of human lenses
Finger-like projections of plasma membrane in the most senescent fiber cells of human lenses
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DOI：
10.1076/ceyr.17.12.1118.5130
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发表时间：
1998-12-01
影响因子：
2
通讯作者：
Takemoto, LJ
中科院分区：
文献类型：
--
作者：
Boyle, DL;Takemoto, LJ
目的.为了证实猴和狒狒晶状体和人透镜纤维细胞中的指状膜投射的发现。将2个月至76岁的正常人晶状体以及年龄相关的核性白内障在室温下浸入2%多聚甲醛-0.2%戊二醛的0.1M二甲胂酸钠缓冲液（pH 7.2）中固定24小时，沿赤道轴沿着切成200-500 μ m厚的切片，在室温下再固定12-18小时，在上升的乙醇系列中脱水并包埋在Lowicryl K4 M中。将半厚切片（0.25-1.0 μ m）切下，吸附在75或100镍缝网格上，用抗MIP 26或鬼笔环肽标记，用2%醋酸双氧铀染色，并在100 kV下通过透射电子显微镜观察。透射电子显微镜的显微照片表明，在两个月和更大的正常晶状体以及核性白内障中，在最衰老的纤维细胞中存在直径为0.16-0.25 μ m，长度为1.0-6.5 μ m的指状质膜突起，具有球根状末端。这些突起似乎覆盖在细胞外空间的膜结构域上，以及沿着质膜的胞质小叶沿着投射到胞质中。这些结果将猴和狒狒晶状体中的发现扩展到人类透镜，并证明这些突起（稀疏地用抗MIP 26的抗血清标记，而不是丝状肌动蛋白）不仅延伸到细胞外空间，而且向内投射到细胞溶质中。
Purpose. To corroborate the findings of finger-like membrane projections in monkey and baboon lenses, in human lens fiber cells.Methods. Normal human lenses, two months to 76 years old, as well as age-related nuclear cataracts, were immersion fixed in 2% paraformaldehyde-0.2% glutaraldehyde in 0.1 M sodium cacodylate buffer pH 7.2 for 24 h at room temperature, cut into 200-500 mu m thick sections along the equatorial axis, fixed for an additional 12-18 h at room temperature, dehydrated in an ascending ethanol series and embedded in Lowicryl K4M. Semi-thick sections (0.25-1.0 mu m) were cut, absorbed onto 75 or 100 nickel slotted grids, labeled with anti-MIP 26 or phalloidin, stained with 2% uranyl acetate and viewed by transmission electron microscopy at 100 kV.Results. Transmission electron microscopy micrographs demonstrated the presence of finger-like plasma membrane projections measuring 0.16-0.25 mu m in diameter and 1.0-6.5 mu m in length with bulbous terminal tips in the most senescent fiber cells in two-month and older normal lenses, as well as, in nuclear cataracts. These projections appeared to overlie furrowed membrane domains in the extracellular space, as well as project into the cytosol along the cytosolic leaflet of plasma membrane.Conclusions. The results extend the findings in monkey and baboon lenses, to the human lens, and demonstrate that these projections, which sparsely label with antiserum against MIP 26, but not filamentous actin, not only extend into the extracellular space, but also project inward into the cytosol.