Welter D A, Hodge L D
Scan Electron Microsc. 1985(Pt 2):879-88.
Chromosome and chromatid alignment in mitotic configurations remains a topic of interest because there is little precise information. For example, reconstruction of mitotic configurations from serial sections collected with transmission electron microscopy has proven to be neither practical nor a sensitive method for conceptualizing these arrangements. Similarly light microscopy has been even more unsatisfactory because of its limited resolution and lack of three-dimensional capabilities. These limitations conceivably could be overcome by visualization of mitotic configurations by scanning electron microscopy (SEM). However, SEM has its limitations, of which the most obvious with regard to visualization of mitotic configurations, is that such structures in dividing cells are obscured from the beam by membranes, cellular organelles, and the mitotic apparatus. These "contaminants," we have found, can be removed by the appropriate procedure such that a direct three-dimensional visualization of intact life-like mitotic configurations of chromatids from mammalian cells is possible. We also demonstrate that these configurations, although some artifacts may exist, retain the same basic shape and chromatid arrangements throughout metaphase, anaphase, and telophase when compared to configurations isolated with a non-ionic detergent and neutral buffers.
有丝分裂构型中的染色体和染色单体排列仍然是一个备受关注的话题，因为精确信息很少。例如，事实证明，通过透射电子显微镜收集的连续切片重建有丝分裂构型，对于理解这些排列既不实用也不灵敏。同样，光学显微镜由于其有限的分辨率和缺乏三维观察能力，情况更不理想。通过扫描电子显微镜（SEM）观察有丝分裂构型，这些限制可能会被克服。然而，SEM也有其局限性，就有丝分裂构型的观察而言，最明显的是，分裂细胞中的此类结构会被细胞膜、细胞器和有丝分裂装置遮挡而无法被电子束观察到。我们发现，通过适当的程序可以去除这些“污染物”，从而能够直接对哺乳动物细胞染色单体完整的、栩栩如生的有丝分裂构型进行三维观察。我们还证明，这些构型尽管可能存在一些假象，但与用非离子去污剂和中性缓冲液分离得到的构型相比，在整个中期、后期和末期都保持相同的基本形状和染色单体排列。
