Zernicka-Goetz M, Kubiak J Z, Antony C, Maro B
Département de Biologie du Développement, Université Paris VII, France.
Mol Reprod Dev. 1993 Jun;35(2):165-75. doi: 10.1002/mrd.1080350210.
In metaphase II arrested rat oocytes (M II), microtubules were found in the taper-shaped meiotic spindle and in the cytoplasm as asters and free microtubules. Whereas spindle microtubules were acetylated, those located in the cytoplasm were not. Cytoplasmic microtubules were also labile as assessed by mild cooling. In contrast to mouse oocytes, rat microtubule organizing centers (MTOCs) did not react with MPM-2 antibody by immunofluorescence despite the fact that this antibody reacts with several proteins as shown by immunoblot. However, cytoplasmic MTOCs in M II-arrested rat oocytes could be detected by their nucleating capacity in the presence of taxol, a drug that induced the formation of numerous cytoplasmic asters. In addition, taxol caused a change in the spindle shape and the formation of astral microtubules at the spindle poles. Meiotic spindles (as well as chromosomes devoid of microtubules after nocodazole-treatment) were overlaid by an actin-rich domain. Spontaneous abortive activation led to the extrusion of the second polar body followed by another metaphase arrest--metaphase III; however, normal spindles did not form and dispersed chromosomes surrounded by microtubules were observed. Electron microscopic studies confirmed these observations and revealed that the kinetochores, are located deep within the chromosomes in contrast to mouse kinetochores, and this might be responsible for the absence of a metaphase III spindle in the rat oocyte. Induced activation caused transition to interphase with the formation of a characteristic microtubule network. This study shows that there are several significant differences in the cytoskeletal organization of rat and mouse oocytes.
在中期 II 阻滞的大鼠卵母细胞（M II）中，在锥形减数分裂纺锤体以及细胞质中发现了微管，呈星体和游离微管形式。纺锤体微管被乙酰化，而位于细胞质中的微管未被乙酰化。通过轻度冷却评估发现，细胞质微管也不稳定。与小鼠卵母细胞不同，尽管免疫印迹显示该抗体可与多种蛋白质反应，但大鼠微管组织中心（MTOC）通过免疫荧光未与 MPM - 2 抗体发生反应。然而，在存在紫杉醇（一种诱导形成大量细胞质星体的药物）的情况下，通过其成核能力可检测到 M II 阻滞的大鼠卵母细胞中的细胞质 MTOC。此外，紫杉醇导致纺锤体形状改变以及在纺锤体极形成星体微管。减数分裂纺锤体（以及用诺考达唑处理后无微管的染色体）被富含肌动蛋白的区域覆盖。自发的流产性激活导致第二极体挤出，随后再次进入中期阻滞——中期 III；然而，未形成正常纺锤体，观察到被微管包围的分散染色体。电子显微镜研究证实了这些观察结果，并揭示与小鼠动粒不同，大鼠动粒位于染色体深处，这可能是大鼠卵母细胞中不存在中期 III 纺锤体的原因。诱导激活导致向间期转变并形成特征性微管网络。这项研究表明，大鼠和小鼠卵母细胞的细胞骨架组织存在若干显著差异。
