【作者】 李俊；

【导师】 刘红林； 王林云；

【作者基本信息】 南京农业大学 ， 动物遗传育种与繁殖， 2003， 硕士

【摘要】 完全生长的小鼠卵泡卵根据染色质构型可分为两种类型，即SN型和NSN型。SN型，即surrounded nucleolus，染色质高度凝集，集中围绕在核仁周围；NSN型，即non-surrounded nucleolus，染色质结构较松散，均匀分布于核中。又根据卵周围的卵丘细胞的有无将卵泡卵分成四种类型，即COC-NSN型(有卵丘细胞的NSN型卵)、COC-SN(有卵丘细胞的SN型卵)、DO-NSN(无卵丘细胞的NSN型卵)和DO-SN(无卵丘细胞的SN型卵)。本研究比较了各类型卵减数分裂过程中染色质构型、体外成熟能力以及Dnase Ⅰ和S1核酸酶敏感性变化。 1．卵泡卵用0.1μg／ml的Hoechst 33342短暂染核后在低强度汞灯光线下短时间内(低于15秒)观察可成功地将不同染色质结构的卵子分开，而且该操作程序不影响卵子的减数分裂能力(P＞0.05)。 2．完全生长的卵泡卵子中SN型比例为63.4％，NSN型为36.6％。在COC卵子中，SN型与NSN型的比例分别为72.5％，27.5％；DO卵子中，SN型与NSN型的比例分别为59.2％，40.8％。DO卵中NSN型卵子的比例显著高于COC卵中NSN型卵子的比例，SN型卵则相反(p＜0.01)。 3．各类型卵子体外减数分裂的能力存在极显著差异(p＜0.01)。生发泡破裂(GVBD)发育至第一次减数分裂中期(MI)能力，SN型卵高于NSN型，COC卵中的NSN型高于DO中的NSN型。排出第一极体(PBI)发育至第二次减数分裂中期(MII)的能力，SN型卵高于NSN型卵，COC卵中的NSN和SN型分别高于DO中的NSN型和SN型。 4．GV期NSN、SN型卵子DNase Ⅰ敏感性无显著差异(P＞0.05)，而在体外成熟培养后减数分裂的MI期S1核酸酶的敏感性NSN型卵显著高于SN型(P＜0.01)，在MII期两种类型卵子S1核酸酶的敏感性无显著差异(P＞0.05)。 总之，SN型卵与NSN型卵在染色质构型、GVBD能力、排出PBI能力与MI期S1核酸酶敏感性方面存在显著的差异。卵成熟前的生长过程中卵丘细胞的存在对卵减数分裂能力的获得性有重要作用。卵丘细胞与染色质构型间存在着协同作用。更多还原

【Abstract】 According to chromatin organization, full growing mouse follicle oocytes were identified as SN-type, whose condensed chromatin surrounded nucleolus, or NSN-type, whose decondensed chromatin distributed in almost whole nuclear. Surrounded by cumulus, oocytes were also identified as COC-NSN or COC-SN, otherwise they were identified as DO-NSN or DO-SN. The objection of this study was to research the difference of each type oocytes in chromatin organization, mature competence and nuclease sensitivity in vitro.Dyed by 0. 1μg/ml Hoechst 33342 for 10 minutes and exposed to lower irradiation shorter than 5 second oocytes could be successfully grouped without any meiosis competence losing.In full growing follicle oocytes, COC-NSN, COC-SN, DO-NSN and DO-SN were respectively accounted for 8.6%, 22.7%, 28.0% and 40.7%. Total of SN-type oocytes was larger than that of NSN-type oocytes. Among DO oocytes percents of NSN-type oocytes, 40. 8%, was higher than that among COC ooctyes, 27. 5%, while percents of SN-type among DO oocytes, 59. 2%, was lower than that among COC oocytes, 72. 5%.Ratio of oocytes undergoing GVBD and developing to MI stage in SN-type oocytes was higher than in NSN-type ooctyes while in COC-NSN oocytes was higher than in DO-NSN oocytes. Competence of oocytes’ developing to MII after excluding FBI in SN-type oocytes was also higher than in NSN-type oocytes while in COC-NSN and in COC-SN oocytes were higher than in DO-NSN oocytes and in DO-SN oocytes respectively.The DNase I sensitivity of each type oocytes in GV stage didn’ t show significant difference. But NSN-type oocytes undergoing GVBD had more S1 nuclease sensitivity than SN-type oocytes in same stage while no significant difference between COC-type oocytes and DO-type oocytes. Little difference among oocytes in Mil stage in S1 nuclease sensitivity was found.On the whole, significant difference exists between NSN-type and SN-type oocytes in chromatin organization, competence of undergoing GVBD or excluding PBI and in MI stage S1 nuclease sensitivity. Cumulus surround growing oocytesare playing important roles on oocytes’ obtaining meiosis competence, and are also in coordination with chromatin organization.更多还原