CELL CLEAVAGE - ULTRASTRUCTURAL EVIDENCE AGAINST EQUATORIAL STIMULATION BY ASTER MICROTUBULES
CELL CLEAVAGE - ULTRASTRUCTURAL EVIDENCE AGAINST EQUATORIAL STIMULATION BY ASTER MICROTUBULES
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DOI：
10.1016/0014-4827(79)90309-4
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发表时间：
1979-01-01
影响因子：
3.7
通讯作者：
SCHROEDER, TE
中科院分区：
文献类型：
--
作者：
ASNES, CF;SCHROEDER, TE
细胞分裂在空间和时间上与核分裂相协调。在星体分裂中，就像发生在海胆卵中一样，协调是由有丝分裂的母细胞完成的。两种紫菀的微管可能在细胞的赤道处交叉。因为它们交叉，或者通过其他结构，更多的微管可能与赤道皮层而不是极地皮层相互作用。星体射线的微管成分可能会对赤道皮层产生不同的劈裂收缩刺激。一种增强微管可见性的固定方法表明，在有丝分裂的任何阶段，aster微管都不会在赤道皮层交叉，这与卵裂刺激有关。紫菀微管在后期逐渐延伸更远，但在卵中这两个阵列占据相互排斥的半球。在有丝分裂的所有阶段，采用另一种固定方法，产生更传统的微管形态，系统地在赤道和两极分别在平行和垂直于有丝分裂装置轴线的切片上计数穿透皮层的微管。前期、中期、后期早期和中期均未见赤道皮层微管。在此期间，在极皮层观察到少量微管。在后期，赤道皮层中有一些微管，但在极地皮层中观察到更多的微管。卵赤道微管数量与卵裂刺激时间之间没有明显的正相关关系。核分裂和细胞分裂之间的协调不是通过赤道皮层微管数量的简单增加来实现的。
Cell cleavage is spatially and temporally corrdinated with karyokinesis. In astral division, as occurs in sea urchin eggs, coordination is accomplished by the mitotic asters. Microtubules of the 2 asters may cross at the cell''s equator. Because they cross, or by some other configuration, more microtubules may interact with the equatorial cortex than with the polar cortex. Microtubule component of astral rays may differentially stimulate the equatorial cortex for cleavage contraction. A fixation procedure which enhances visibility of microtubules showed that aster microtubules do not cross at the equatorial cortex at any stage of mitosis relevent to the cleavage stimulation. Aster microtubules extend progressively farther during anaphase, but the 2 arrays occupy mutually exclusive hemispheres in the egg. Using another fixation procedure which results in more conventional microtubule morphology, microtubules penetrating the cortex were systematically counted at both the equator and the poles in sections cut parallel and perpendicular to the axis of the mitotic apparatus, respectively, at all stages of mitosis. Microtubules in the cortex of the equator were not seen during prometaphase, metaphase, early anaphase or mid-anaphase. Small numbers of microtubules were observed in the polar cortex during this time. By late anaphase there are some microtubules in the equatorial cortex but many more are observed in the polar cortex. There is apparently no positive correlation between microtubule numbers at thc egg equator and the timing of cleavage stimulation. Coordination between karyokinesis and cell cleavage is achieved by a process other than the simple numerical increase of microtubules at the equatorial cortex.