Experimental analysis of second cleavage in the mouse
Experimental analysis of second cleavage in the mouse
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DOI：
10.1093/humrep/17.12.3178
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发表时间：
2002-12-01
影响因子：
6.1
通讯作者：
Gardner, RL
中科院分区：
文献类型：
--
作者：
Gardner, RL
背景：哺乳动物的孕体在4细胞阶段通常具有近似规则的四面体形状。在兔子中，这归因于两个2-细胞卵裂球都是平行分裂的，但在胞质分裂之前或期间，第二个卵裂球的动物-植物轴旋转了大约90度。本研究的目的是确定这是否也适用于小鼠。方法和结果：首先，在规则的四面体4-细胞概念的荧光微球施加到植物极性区域的一个或两个卵裂球在2-细胞阶段的分布进行了分析。其次，还研究了在将前卵裂球间隙凝胶化以防止卵裂球旋转后，2-细胞阶段形成规则四面体4-细胞孕体的能力。两个实验都没有得到支持第二次卵裂时卵裂球旋转的证据。相反，这些发现与由一个卵裂球经向分裂和另一个卵裂球大致赤道分裂产生的4细胞孕体的规则四面体形式一致。结论：小鼠的第二次卵裂通常产生具有三种不同类型卵裂球的4细胞孕体。赤道分裂的产物包括受精卵的所有轴向水平，而赤道分裂的产物只获得其植物或动物的一半。
BACKGROUND: Mammalian conceptuses typically have an approximately regular tetrahedral shape at the 4-cell stage. In the rabbit, this has been attributed to both 2-cell blastomeres dividing meridionally, but with the animal-vegetal axis of the second blastomere to divide rotating through roughly 90degrees before or during cytokinesis. The aim of the present study was to ascertain whether this was also true for the mouse. METHODS AND RESULTS: First, the distribution in regular tetrahedral 4-cell conceptuses of fluorescent microspheres applied to the vegetal polar region of one or both blastomeres at the 2-cell stage was analysed. Second, the ability of 2-cell stages to form regular tetrahedral 4-cell conceptuses after the previtelline space had been gelated to prevent blastomeres from rotating was also investigated. Neither experiment yielded evidence supporting blastomere rotation during second cleavage. Rather, the findings were consistent with the regular tetrahedral form of 4-cell conceptus resulting from meridional division of one blastomere and approximately equatorial division of the other. CONCLUSIONS: Second cleavage in the mouse typically yields 4-cell conceptuses with three distinct types of blastomere. While both products of the meridional division include all axial levels of the zygote, those of the equatorial division acquire only its vegetal or animal half.