Crozet N, Dahirel M, Chesne P
INRA, Unité de Physiologie animale, Jouy-en-Josas, France.
Microsc Res Tech. 2000 Jun 1;49(5):445-50. doi: 10.1002/(SICI)1097-0029(20000601)49:5<445::AID-JEMT6>3.0.CO;2-B.
The inheritance and duplication of the sperm centriole in the sheep zygote was studied by transmission electron microscopy. We found two centrioles at one pole and a single centriole at the opposite pole of the first mitotic spindle, in monospermic eggs, 20-21 hours postinsemination. This indicated both duplication and relocation of centrioles to opposite spindle poles during fertilization. The absence of centrioles in mature sheep oocytes was confirmed. Following activation by the calcium ionophore A 23187, mature oocytes entered mitosis and formed a bipolar spindle 18 hours later. Centrioles were not detected in the mitotic spindle of parthenogenotes. Androgenetic eggs were obtained by excision of the anaphase II/telophase II meiotic spindle of fertilized eggs. They were capable of undergoing mitosis and formed one or two bipolar spindle(s) in monospermic and dispermic eggs, respectively, 20-24 hours postinsemination. In two monospermic androgenetic eggs, two centrioles were found at one pole and a single centriole at the opposite pole of the first mitotic spindle. Three centrioles were also observed in another androgenetic egg in prometaphase of the first mitotic division, in close vicinity to the sperm neck-piece. These data provide evidence that the sperm centriole do reproduce and occupy a pivotal position on opposite spindle poles at syngamy. Altogether, the present findings suggest that centrioles of sheep zygotes are paternally derived.
通过透射电子显微镜研究了绵羊受精卵中精子中心粒的遗传和复制情况。我们发现，在授精后20 - 21小时的单精卵中，第一次有丝分裂纺锤体的一极有两个中心粒，相对的另一极有一个中心粒。这表明在受精过程中中心粒发生了复制并迁移到纺锤体相对的两极。成熟绵羊卵母细胞中不存在中心粒这一点得到了证实。经钙离子载体A 23187激活后，成熟卵母细胞进入有丝分裂，并在18小时后形成双极纺锤体。孤雌生殖细胞的有丝分裂纺锤体中未检测到中心粒。通过切除受精卵后期II/末期II减数分裂纺锤体获得雄核发育卵。它们能够进行有丝分裂，在授精后20 - 24小时，单精卵和双精卵分别形成一个或两个双极纺锤体。在两个单精雄核发育卵中，第一次有丝分裂纺锤体的一极发现有两个中心粒，相对的另一极有一个中心粒。在另一个处于第一次有丝分裂前期的雄核发育卵中，也观察到三个中心粒，紧邻精子颈部。这些数据证明精子中心粒确实会复制，并在配子融合时在纺锤体相对两极占据关键位置。总之，目前的研究结果表明绵羊受精卵的中心粒来源于父本。
