López-Velázquez G, Márquez J, Ubaldo E, Corkidi G, Echeverría O, Vázquez Nin G H
Department of Biology, Faculty of Sciences, UNAM, Mexico.
Histochem Cell Biol. 1996 Feb;105(2):153-61. doi: 10.1007/BF01696155.
The arrangement of compact chromatin of G0 lymphocytes was studied in three-dimensional reconstructions of the ensemble of the chromatin and of individual compact chromatin bodies. Rat spleen was serially cut and sections were contrasted with procedures preferential for DNA. Electron microscopy images were digitized, processed, and displayed using a commercial software package, complemented by a system for three-dimensional reconstruction and analysis developed by us on an IBM-compatible microcomputer provided with an image acquisition board. The reconstructions showed a continuous layer of compact chromatin in contact with the nuclear envelope that prevents the automatic recognition of individual chromatin clumps. The ensemble of the arrangement of compact chromatin was found to be very similar in different lymphocytes. After morphological filtering procedures, the initial mass was divided into individual bodies of compact chromatin, which were tagged. Most of these bodies contact the nuclear envelope. The number of bodies as well as the number of contacts with the envelope are similar and correspond to a haploid number of chromosomes. The largest body is always the one containing nucleolus-associated chromatin. When the cell has two nucleoli, the nucleolus-associated chromatin bodies contact the envelope in diametrically opposed areas. This feature was also described in rat liver cells. It is concluded that: (a) the individualized compact chromatin bodies do not correspond to an entire chromosome or to a pair of chromosomes; (b) the arrangement of compact chromatin is not identical in each G0 lymphocyte, but there are patterns that are repeated with limited changes; and (c) there are common features that appear in different cell types of individuals of the same species.
在染色质整体和单个紧密染色质体的三维重建中，研究了G0淋巴细胞紧密染色质的排列。对大鼠脾脏进行连续切片，并用优先针对DNA的方法对切片进行对比。将电子显微镜图像数字化、处理并使用商业软件包显示，同时辅以我们在配备图像采集板的IBM兼容微型计算机上开发的三维重建和分析系统。重建结果显示，紧密染色质的连续层与核膜接触，这妨碍了对单个染色质团块的自动识别。发现在不同淋巴细胞中，紧密染色质的排列整体非常相似。经过形态学过滤程序后，初始物质被分割成单个紧密染色质体，并进行标记。这些体中的大多数与核膜接触。体的数量以及与核膜的接触数量相似，且与单倍体染色体数量相对应。最大的体总是包含与核仁相关染色质的那个。当细胞有两个核仁时，与核仁相关的染色质体在直径相对的区域与核膜接触。这一特征在大鼠肝细胞中也有描述。得出以下结论：(a) 个体化的紧密染色质体并不对应于整条染色体或一对染色体；(b) 每个G0淋巴细胞中紧密染色质的排列并不相同，但存在有限变化下重复出现的模式；(c) 在同一物种个体的不同细胞类型中存在共同特征。
