体内外成熟过程中小鼠卵母细胞纺锤体形态和皮质颗粒分布的比较

Distinctions in Meiotic Spindle Configuration and Distribution of Cortical Granules during in vitro and in vivo Maturation of Mouse Oocytes

目的:了解体内外成熟过程中小鼠卵母细胞减数分裂进程、纺锤体形态、皮质颗粒分布的差异。方法:分别收集体内和体外成熟2h、4h、8h、16h的卵母细胞,用免疫荧光法标记微管,Hochest33258标记染色体,FITC-LCA标记皮质颗粒,分别观察卵母细胞减数分裂进程、纺锤体形态和皮质颗粒分布,并进行比较。结果:与体外成熟卵母细胞相比,体内成熟的卵母细胞减数分裂进程高度一致。体内成熟的卵母细胞减数分裂中期的纺锤体呈两端逐渐变细的"纺锤状",且靠近卵膜(100%);而大多数体外成熟的卵母细胞的纺锤体两端宽大,呈"桶状",在第一次减数分裂中期和第二次减数分裂中期各有34.29%和43.24%靠近卵膜。体外成熟卵母细胞在第一次减数分裂中期和第二次减数分裂中期出现无皮质颗粒区的比例(分别为12.5%和75%)明显低于体内成熟卵(均为100%)。结论:体内和体外成熟的卵母细胞在减数分裂进程、纺锤体的形态和运动、皮质颗粒分布等方面均存在巨大的差异。体外成熟的卵母细胞在这些方面的变化可能与其发育能力下降有关。

Objective： To observe distinctions in meiotic progression, spindle configuration and distribution of cortical granules during in vitro （IVO） and in vivo maturation （IVM） of mouse oocytes. Methods： IVO and IVM oocytes were collected at 2 h, 4 h, 8 h, 16 h of maturation. Tubulins were labeled with immunofluorescence and chromosomes were labeled with Hochest33258. Cortical granules （CGs） were labeled with fluorescein isothiocyanate- lens culinaris agglutinin （FITC-LCA）. Oocyte meiotic progression, spindle configuration and distribution of CGs were assessed by laser cofocal microscopy. Results： IVO oocytes appeared more synchronously during meiotic progression than IVM oocytes. Metaphase spindles in the IVO oocytes were compact, displayed tapered poles and closed to the oolemma （100%）. However, the IVM oocytes exhibited barrel-shaped spindles with flat poles. Only 34.29% at M1 and 43.24% at MII in the IVM oocytes were near the oolemma. The percentages of the IVM oocytes formed cortical granule-free domain at MI and MII stages （12.5% and 75.0%, respectively） were significantly lower than those of the IVO oocytes （100%）. Conclusion： Differences were significant during meiotic progression, spindle configuration and distribution of CGs between IVO and IVM oocytes, which may be a reason that developmental competence of IVM oocytes decreases.