Bailey J, Gingell D
Department of Genetics, University of Leicester, UK.
J Cell Sci. 1988 Jun;90 ( Pt 2):215-24. doi: 10.1242/jcs.90.2.215.
We have examined the contacts made by explanted chick heart and limb bud fibroblasts after 24-48 h on glass, using quantitative interference reflection microscopy (IRM). Contacts beneath very thin cytoplasmic lamellae were avoided because the images of such contacts depend on the thickness of the lamellae. Plaque-like focal contacts, distinguished on the basis of shape and low irradiance (darkness), are intimate adhesions to the substratum. These images can be interpreted if it is assumed that microfilaments associated with the lower membrane increase the local cytoplasmic refractive index. The range of irradiances measured for focal contacts was found to be rather wide, and our modelling shows that the most likely explanation for this is that the images receive variable contributions from the adjacent cytoskeleton. For this reason it is particularly difficult to assign a characteristic thickness for these contacts from IRM data. Close contacts, seen principally as 'grey' regions under migrating cells at the edges of the explants, also show a wide range of irradiances. Unlike focal contacts, it is not necessary to postulate any involvement of the cytoskeleton in their images and they can be modelled as regions where an aqueous glycocalyx zone about 20-30 nm thick separates the membrane bilayer from the glass. Paler grey regions that also look like close contacts are apparently formed where the cell surface has lifted several tens of nanometres from the glass.
我们使用定量干涉反射显微镜（IRM），检查了移植的鸡心脏和肢体芽成纤维细胞在玻璃上培养24至48小时后的接触情况。非常薄的细胞质薄片下方的接触被避开，因为此类接触的图像取决于薄片的厚度。基于形状和低辐照度（暗度）区分的斑块状粘着斑是与基质的紧密粘附。如果假设与较低膜相关的微丝增加了局部细胞质折射率，那么这些图像就可以得到解释。发现粘着斑测量的辐照度范围相当宽，我们的模型表明，对此最可能的解释是图像从相邻的细胞骨架获得了可变的贡献。因此，从IRM数据中为这些接触指定一个特征厚度特别困难。紧密接触主要表现为外植体边缘迁移细胞下方的“灰色”区域，其辐照度范围也很宽。与粘着斑不同，在其图像中不必假定细胞骨架有任何参与，它们可以被建模为一个区域，在该区域中，约20至30纳米厚的水性糖萼区将膜双层与玻璃分隔开。看起来也像紧密接触的较浅灰色区域显然是在细胞表面从玻璃上抬起几十纳米的地方形成的。
