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目的观察100μmol/L丁内酯-I(BL-I)对小鼠卵母细胞的体外成熟、染色质构型及超微结构的影响。方法实验组小鼠未成熟卵用“两步法”培养,先用BL-I培养液培养6 h,然后再用成熟培养液培养;对照组直接用成熟培养液培养,观察其生发泡破裂(GVBD)和第一极体形成的过程。将BL-I培养液培养6 h前后的卵母细胞分别固定行Hochest33342染色及制作电子显微镜标本,比较染色质构型及超微结构的变化。结果BL-I培养液培养小鼠未成熟卵6 h,实验组卵母细胞GVBD的发生率(21.5%)明显低于对照组(82.3%)(P=0.001)。BL-I的抑制作用消除后,实验组卵母细胞GVBD发生率(96.9%)和成熟率(86.1%)与对照组(分别为97.3%和83.3%)无差异,但GVBD和成熟过程明显加速。BL-I抑制卵母细胞核成熟6 h,部分卵母细胞(32.8%)的染色质凝集,染色质围绕核仁型(SN)和非围绕核仁型(NSN)卵母细胞的比例(50.8%和16.4%)较培养前(69.2%和30.8%)明显下降;卵丘颗粒细胞的伸展未受影响,卵母细胞胞质的超微结构未出现明显异常,皮质颗粒和线粒体的形态及分布与对照组相似。结论BL-I能可逆性抑制体外培养的小鼠卵母细胞的核成熟,抑制作用消除后,卵母细胞成熟能力不受影响,但GVBD和第一极体的形成过程明显加速;在BL-I抑制卵母细胞核成熟的过程中,染色质构型发生变化,部分NSN型转化为发育能力更高的SN型,而胞质的超微结构未出现明显异常,有待进一步研究。
Objective To observe the effects of 100 μmol / L butyrolactone-I (BL-I) on mouse oocyte maturation, chromatin structure and ultrastructure. Methods The immature eggs of experimental mice were cultured with BL-I culture medium for 6 h and then cultured in mature culture medium. The control group was cultured directly in mature culture medium to observe the germinal vesicle formation Rupture (GVBD) and the formation of the first polar body. The oocytes cultured in BL-I culture medium for 6 h were fixed with Hochest33342 staining and electron microscopy to compare chromatin structure and ultrastructure changes. Results The immature oocytes of mice were cultured in BL-I medium for 6 h. The incidence of oocytes GVBD in experimental group (21.5%) was significantly lower than that of control group (82.3%) (P = 0.001). After the inhibition of BL-I was abolished, the incidence of GVBD (96.9%) and maturation rate (86.1%) in experimental group were no different from those in control group (97.3% and 83.3% respectively), but the GVBD and maturation rate were significantly accelerated . BL-I inhibited chromatin condensation of some oocytes (32.8%) at 6 h after nuclear maturation of oocytes, and the ratio of chromatin around nucleolar (SN) and non-nucleated (NSN) oocytes (50.8% And 16.4%, respectively) were significantly lower than those before culturing (69.2% and 30.8%). The extension of ciliary granulosa cells was unaffected and the ultrastructure of oocyte cytoplasm did not show obvious abnormalities. The morphology and distribution of cortical granules and mitochondria Control group similar. CONCLUSION: BL-I can reversibly inhibit the nuclear maturation of mouse oocytes cultured in vitro. After the inhibition is abolished, the oocyte maturation ability is not affected, but the formation of GVBD and the first polar body is accelerated obviously. In BL- I inhibits the nuclear maturation of oocytes, the chromatin configuration changes, some of the NSN type into more capable SN type, and the cytoplasmic ultrastructure does not appear significant abnormality, pending further study.