Freeze-fracture studies of the developing cell surface. II. Particle- free membrane blisters on glutaraldehyde-fixed corneal fibroblasts are artefacts
Freeze-fracture studies of the developing cell surface. II. Particle- free membrane blisters on glutaraldehyde-fixed corneal fibroblasts are artefacts
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发育中的细胞表面的冷冻断裂研究。
DOI：
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发表时间：
1978
影响因子：
7.8
通讯作者：
Elizabeth D. Hay
中科院分区：
文献类型：
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作者：
Elizabeth D. Hay
我们通过切片和冷冻断裂法描述了四类与戊二醛固定的胚胎角膜成纤维细胞相关的无膜内颗粒（IMP）膜泡或“水泡”：（a）附着在细胞膜上的单个水泡;（B）游离（分离）囊泡;（c）髓磷脂图形;（d）类似于其他人在神经生长锥上描述的“土丘”的多泡突起。不含IMP的膜结合水泡不含研磨的细胞质或细胞器，与胰蛋白酶分离的成纤维细胞上的水泡相反，我们在这里展示了含有细胞质和富含IMP的膜。胚胎角膜中的无IMP膜泡是固定的伪影，这一点通过以下两点得到证实：（a）在未经醛固定的冷冻和断裂的成纤维细胞复制品中不存在这些膜泡;（B）在戊二醛和四氧化锇组合固定的成纤维细胞切片中不存在这些膜泡。我们认为，锇的加入防止postfixation运动的膜脂质，特别是带负电荷的“流体”脂质，其他人已经表明，能够相当大的流动性醛固定后单独。最近的文献表明，在分泌过程和神经生长中存在膜起泡，但在评估此类无IMP水泡的功能意义之前，应考虑此处所示类型的膜流动性。
We describe, in sections and by freeze-fracture, four classes of intramembrane particle (IMP)-free membrane blebs or "blisters" associated with glutaraldehyde-fixed embryonic corneal fibroblasts: (a) Single blisters attached to the cell membrane; (b) free (detached) vesicles; (c) myelin figures; (d) multivesicular protrusions which resemble the "mounds" described by others on nerve growth cones. The IMP-free, membrane-bounded blisters contain no ground cytoplasm or organelles, in contrast to blebs on trypsin-isolated fibroblasts, which we show here do contain cytoplasm and IMP-rich membranes. That the IMP- free membrane blisters in embryonic corneas are artefacts of fixation is demonstrated by (a) their absence in replicas of fibroblasts frozen and fractured without prior aldehyde fixation and (b) their absence in sections of fibroblasts fixed in a combination of glutaraldehyde and osmium tetroxide. We suggest that the addition of osmium prevents postfixation movement of membrane lipids, especially the negatively charged "fluid" lipids which others have shown are capable of considerable mobility after aldehyde fixation alone. Recent literature has implicated membrane blistering in secretory processes and in growth of nerves, but before the functional significance of such IMP-free blisters is assessed, membrane mobility of the type shown here should be taken into consideration.