Rieder C L
Wadsworth Center for Laboratories and Research, New York State Department of Health, Albany 12201-0509.
Electron Microsc Rev. 1990;3(2):269-300. doi: 10.1016/0892-0354(90)90005-d.
The formation of the astral mitotic spindle is initiated at the time of nuclear envelope breakdown from an interaction between the replicated spindle poles (i.e. centrosomes) and the chromosomes. As a result of this interaction bundles of microtubules are generated which firmly attach the kinetochores on each chromosome to opposite spindle poles. Since these kinetochore fibers are also involved in moving the chromosomes, the mechanism by which they are formed is of paramount importance to understanding the etiology of force production within the spindle. As a prelude to outlining such a mechanism, the dynamics of spindle formation and chromosome behavior are examined in the living cell. Next, the properties of centrosomes and kinetochores are reviewed with particular emphasis on the structural and functional changes that occur within these organelles as the cell transits from interphase to mitosis. Finally, a number of recent observations relevant to the mechanism by which these organelles interact are detailed and discussed. From these diverse data it can be concluded that kinetochore fiber microtubules are derived from dynamically unstable astral microtubules that grow into, or grow by and then interact laterally with, the kinetochore. Moreover, the data clearly demonstrate that the interaction of a single astral microtubule with one of the kinetochores on an unattached chromosome is sufficient to attach the chromosome to the spindle, orient it towards a pole, and initiate poleward motion. As the chromosomes move into the region of the forming spindle more astral microtubules become incorporated into the nascent kinetochore fibers and chromosome velocity decreases dramatically. During this time the distribution of spindle microtubules changes from two overlapping radial arrays to the fusiform array characteristic of metaphase cells.
星状有丝分裂纺锤体的形成始于核膜破裂之时，由复制后的纺锤体极（即中心体）与染色体之间的相互作用引发。这种相互作用产生了微管束，将每条染色体上的动粒牢固地连接到相对的纺锤体极上。由于这些动粒纤维也参与染色体的移动，其形成机制对于理解纺锤体内力产生的病因至关重要。作为概述这种机制的前奏，在活细胞中研究了纺锤体形成和染色体行为的动态变化。接下来，回顾了中心体和动粒的特性，特别强调了随着细胞从间期过渡到有丝分裂，这些细胞器内发生的结构和功能变化。最后，详细讨论了一些与这些细胞器相互作用机制相关的最新观察结果。从这些不同的数据可以得出结论，动粒纤维微管源自动态不稳定的星状微管，这些微管生长进入动粒，或生长并随后与动粒横向相互作用。此外，数据清楚地表明，单个星状微管与未附着染色体上的一个动粒相互作用足以将染色体附着到纺锤体上，使其朝向一极定向，并启动向极运动。随着染色体移入正在形成的纺锤体区域，更多的星状微管被并入新生的动粒纤维中，染色体速度急剧下降。在此期间，纺锤体微管的分布从两个重叠的径向阵列变为中期细胞特有的梭形阵列。
