Follicular growth,differentiation and atresia

Only limited numbers of primordial follicles in mammalian ovary grow and differentiate to reach the stage of dominate follicles and ovulate. 99% of the follicles in the ovary undergo atresia at various stages of development.Regulation of follicular growth, development and atresia is a complex process and involves interactions between endocrine factors and intraovarian regulators. This review summarized: i ) FSH may not be a survival factor in regulating slow-growing preantral follicles. Some locally produced growth factors, activin and orphan receptors might play a more important role at this stage, ii ) Estrogen, activin/inhibin and follistatin coordinate with FSH to regulate and control follicle differentiation, iii) There are two types of follicular atresia induced by apoptosis which originates from GC or oocyte, respectively. Early translation of tPA mRNA into tPA protein in oocyte may be associated with oocytea apoptosis.     

精子和酒精对小鼠卵母细胞激活的比较

对不同卵龄的小鼠卵母细胞被精子和酒精激活后的激活率进行了比较。结果显示,卵母细胞对常规的体外受精和酒精的人工激活的激活率存在卵龄的差异。注射hCG后15～24h的卵母细胞容易被酒精的人工刺激所激活,20h卵龄的卵母细胞激活率最高,平均为81．6％,且速即卵裂率也最高,平均为48％,卵龄更大的卵母细胞激活率降低,而13h的卵母细胞难以被酒精激活。另一方面,13～15h的卵母细胞容易被精子激活而受精,卵龄较大的卵母细胞在体外难以被精子激活受精。这表明,精子和酒精对卵母细胞的激活机制有所不同。     

牛细胞核移植试验初报

体外成熟培养（ＩＶＭ）２３－２４ｈ的牛卵母细胞，去核后用８０Ｖ／ｍｍ，４０μｓ电激活２次（Ｉ组）或不激活（Ⅱ组），然后注入８－３２细胞期体外受精（ＩＶＦ）牛胚胎的卵裂球，再用８０－１００Ｖ／ｍｍ，４０μｓ电激两次诱导卵母细胞与卵裂球融合，两组的融合率（６２．８％与６５．１％）和卵裂率（５５．４％与５１．９％）无显著差异（Ｐ〉０．０５）。全部４１２枚重组卵电激后的融合率是６３．８％（２６３／４１２）     

鲶卵巢发育组织学的初步研究

以鲶卵巢为材料，研究了卵巢和卵母细胞发育的形态结构特点。鲶卵巢的发育划分为６期，其卵母细胞相应地划分为６个时相，第一时相的卵母细胞呈原始分化状态，细胞外具一层细胞质膜，第二时相卵母细胞外不仅具质膜，而且还有滤泡膜和结缔组织膜。第三和第四时相的卵母细胞分化明显，由散在的卵黄沉积逐渐形成大的卵黄颗粒。第四时相卵母细胞具有漏斗状的精孔及椭圆形的精孔细胞。第五时相和第六时相分别为卵子形成和退化吸收时相。     

昆明白小鼠卵母细胞的生发泡移植

为探讨细胞核与细胞质调控减数分裂的机制，对昆明白小鼠GV期卵母细胞进行了GV移植研究．将6～8周龄小鼠GV期卵母细胞分别与6～8周龄和3月龄小鼠GV期卵母细胞进行GV互换，所形成的3种GV～胞质体复合体的融合率(85．0％～89．8％)和3种重组卵母细胞的成熟率(93．9％～96．2％)并不因小鼠年龄的改变而有所变化．经人工活化后，3种重组卵母细胞形成原核期胚和2-细胞期胚的比率(分别为80．5％～85．4％和51．2％～55．4％)也不因不同年龄小鼠卵母细胞所带来的细胞质或细胞核的改变而受到影响．细胞遗传学分析表明成熟的重组卵母细胞表现出正常的核型．     

非洲爪蟾卵母细胞内的螺旋钙波和靶波

该文应用定态线性化的Atri模型方程，描述非洲爪蟾(Xenopus Laevis)卵母细胞内钙波的生成和演化。在忽略细胞边界影响的近似下，得到了爪蟾卵母细胞内螺旋钙波和靶波的解析解。对于远离细胞中心的渐近情形，对应的螺旋波为Archimede型。由此得到的波速、波长和周期均与实验和数值模拟结果吻合。并指出IP3R失活常数必须大于2．43s，才能产生胞内周期钙波。     

RNA-splicing endonuclease structure and function

The RNA-splicing endonuclease is an evolutionarily conserved enzyme responsible for the excision of introns from nuclear transfer RNA (tRNA) and all archaeal RNAs. Since its first identification from yeast in the late 1970s, significant progress has been made toward understanding the biochemical mechanisms of this enzyme. Four families of the splicing endonucleases possessing the same active sites and overall architecture but with different subunit compositions have been identified. Two related consensus structures of the precursor RNA splice sites and the critical elements required for intron excision have been established. More recently, a glimpse was obtained of the structural mechanism by which the endonuclease recognizes the consensus RNA structures and cleaves at the splice sites. This review summarizes these findings and discusses their implications in the evolution of intron removal processes. Received 24 August 2007; received after revision 24 November 2007; accepted 27 November 2007     

牛卵母细胞的采集方法和卵巢贮存条件对其体外成熟的影响

比较了抽吸法和剖切法取得屠宰奶牛卵巢的可用卵母细胞数,并探讨了在卵巢运输过程中温度和时间对卵母细胞成熟率和卵裂率的影响.从屠宰场收集奶牛卵巢158个,用抽吸法抽取了96个卵巢,平均每个卵巢收集可用卵母细胞8.04枚(772枚/96卵巢);用切剖法切割了62个卵巢,平均每个卵巢收集可用卵母细胞18.89枚(1171枚/62卵巢).统计分析证明,两种采集方法获得的可用卵母细胞数差异极显著(p<0.01).将屠宰牛卵巢分别置于20℃～29℃和30℃～38℃的生理盐水中,在6h内收集到卵母细胞的成熟率和卵裂率分别为53.8%、31.7%和63.3%、34.3%,两者之间的差异均不显著(p>0.05).在30℃～38℃温度下,屠宰牛卵巢保存时间超过6h时,卵母细胞的成熟率和卵裂率显著下降,分别为36.1%和0%.与小于2h和2～6h相比差异极显著(p<0.01).     

Cloned pigs derived from somatic cell nuclear transfer embryos cultured in vitro at low oxygen tension

Great progress have been made in animal cloning in China, as evidenced by the live births of cloned cat- tle[1,2], goats[3,4], and sheep[5]. In contrast, pig cloning is still in its infancy though limited fundamental studieshave been conducted[6]. It is g…     

中华绒螯蟹卵子发生中卵母细胞表面和滤泡细胞的超微结构

利用透射电镜技术观察了中华绒螯蟹卵子发生过程中卵母细胞表面和滤泡细胞超微结构的变化.结果显示:从卵原细胞期到卵黄大量合成时期,滤泡细胞逐渐向卵母细胞迁移,细胞膜向外伸出许多突起,胞质中的细胞器逐渐增多,它们与卵黄蛋白物质一同移入卵周隙.到卵黄合成晚期,滤泡细胞逐渐解体.与此同时卵母细胞表面在卵黄发生初期可见微胞饮小泡;卵黄大量发生期出现大量微绒毛;卵黄合成晚期,卵黄膜形成,卵黄膜上出现多条通道,这些结构为卵母细胞吸收来自滤泡细胞的卵黄蛋白物质提供了保障.