first meiotic division

Maternal nondisjunction was demonstrated in 14 cases, ten cases were due to nondisjunction in the first meiotic division and 4 cases were caused by nondisjunction during the second meiotic division.

证明为母源的14例（73.7%），其中10例是第一次减数分裂不分离，4例是第二次减数分裂不分离。

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Scanning electron microscopic observations of chromosomes of the first prophase of meiotic division in spermatocyte of Bana nigromaculatas

黑斑蛙减数分裂前期Ⅰ的扫描电镜观察

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A four-flagellar stage appeared after the first meiotic nuclear division of spermatocyte.

雄配子发育较为缓慢，精母细胞第一次核减数分裂之后经历了一个四鞭毛期。

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Fully-grown mammalian oocytes are arrested at the prophase of the first meiotic division within the ovarian follicles.

哺乳动物卵巢中的卵母细胞的发育停滞在第一次减数分裂前期的双线期。

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Since crossing over can occur during the first meiotic division, it does allow for some genetic variation in the offspring.

在第一次减数分裂的过程中可以发生交换现象，因而在后代中有遗传变化。

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Reduction division& The first meiotic division, so called because at this stage the chromosome number per cell is reduced from diploid to haploid.

第一次减数分裂，每个细胞的染色体数目从二倍性减少为单倍性。

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Synaptonemal complex ( SC) is a transient structure which happened in eukaryotic nuclei during the first meiotic division when homologous chromosomes are pairing.

联会复合体（Synaptonemal Complex，SC）是真核生物减数分裂前期I同源染色体配对时形成的一种核内临时结构。

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Conclusion: The twin girls originate from dizygotic and the extra chromosome 21 of the elder sister is from nondisjunction during the first meiotic division of the mother.

结论孪生姐妹为异卵孪生，孪生姐姐额外的21号染色体来自于母亲第1次减数分裂不分离。

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Dictyotene& The stage of the first meiotic division in which a human oocyte remains from late fetal life until ovulation.

第一次减数分裂的一个阶段，从胎儿晚期直到排卵，人类卵母细胞一直处在这个阶段。

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Microspore abortion of male sterility line of Cotton "Lang A" begins during microsporocyte period. First meiotic division is the main period in its abortion, It almost cannot realise the normal meiosis and form the normal microspore.

棉花阆A雄性不育系小孢子败育，从小孢子母细胞就已经开始，减数分裂的第一次分裂是败育的主要时期，基本上不能完成减数分裂，不能形成正常小孢子。

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In dandelion ( Taraxacum), for example, the chromosomes of the megaspore mother cell remain in one cell after the first meiotic division, forming a restitution nucleus.

例如在蒲公英中，在第一次减数分裂后，大孢子母细胞的染色体仍在一个细胞中，形成一个再组核。

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Bivalent& A pair of homologous chromosomes in association, as seen at metaphase of the first meiotic division.

发生联会时的一对同源染色体，见于第一次减数分裂的中期。

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