Li G P, Chen D Y, Lian L, Sun Q Y, Wang M K, Song X F, Meng L, Schatten H
State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100080 China.
J Exp Zool. 2001 Apr 15;289(5):322-9.
A series of experiments were designed to evaluate the meiotic competence of mouse oocyte germinal vesicle (GV) in rabbit ooplasm. In experiment 1, an isolated mouse GV was transferred into rabbit GV-stage cytoplast by electrofusion. It was shown that 71.8% and 63.3% of the reconstructed oocytes completed the first meiosis as indicated by the first polar body (PB1) emission when cultured in M199 and M199 + PMSG, respectively. Chromosomal analysis showed that 75% of matured oocytes contained the normal 20 mouse chromosomes. When mouse spermatozoa were microinjected into the cytoplasm of oocytes matured in M199 + PMSG and M199, as many as 59.4% and 48% finished the second meiosis as revealed by the second polar body (PB2) emission and a few fertilized eggs developed to the eight-cell stage. In experiment 2, a mouse GV was transferred into rabbit MII-stage cytoplast. Only 13.0-14.3% of the reconstructed oocytes underwent germinal vesicle breakdown (GVBD) and none proceeded past the MI stage. When two mouse GVs were transferred into an enucleated rabbit oocyte, only 8.7% went through GVBD. In experiment 3, a whole zona-free mouse GV oocyte was fused with a rabbit MII cytoplast. The GVBD rates were increased to 51.2% and 49.4% when cultured in M199 + PMSG and M199, respectively, but none reached the MII stage. In experiment 4, a mouse GV was transferred into a partial cytoplasm-removed rabbit MII oocyte in which the second meiotic apparatus was still present. GVBD occurred in nearly all the reconstructed oocytes when one or two GVs were transferred and two or three metaphase plates were observed in ooplasm after culturing in M199 + PMSG for 8 hr. These data suggest that cytoplasmic factors regulating the progression of the first and the second meioses are not species-specific in mammalian oocytes and that these factors are located in the meiotic apparatus and/or its surrounding cytoplasm at MII stage.
设计了一系列实验来评估小鼠卵母细胞生发泡（GV）在兔卵细胞质中的减数分裂能力。在实验1中，通过电融合将分离的小鼠GV转移到兔GV期细胞质体中。结果显示，当分别在M199和M199 + PMSG中培养时，71.8%和63.3%的重构卵母细胞完成了第一次减数分裂，表现为第一极体（PB1）排出。染色体分析表明，75%的成熟卵母细胞含有正常的20条小鼠染色体。当将小鼠精子显微注射到在M199 + PMSG和M199中成熟的卵母细胞细胞质中时，分别有多达59.4%和48%的卵母细胞完成了第二次减数分裂，表现为第二极体（PB2）排出，并且一些受精卵发育到了八细胞期。在实验2中，将小鼠GV转移到兔MII期细胞质体中。只有13.0 - 14.3%的重构卵母细胞发生了生发泡破裂（GVBD），且没有一个能超过MI期。当将两个小鼠GV转移到去核的兔卵母细胞中时，只有8.7%发生了GVBD。在实验3中，将整个无透明带的小鼠GV卵母细胞与兔MII期细胞质体融合。当分别在M199 + PMSG和M199中培养时，GVBD率分别提高到了51.2%和49.4%，但没有一个达到MII期。在实验4中，将小鼠GV转移到部分去除细胞质但仍存在第二次减数分裂装置的兔MII期卵母细胞中。当转移一个或两个GV时，几乎所有重构卵母细胞都发生了GVBD，在M199 + PMSG中培养8小时后，在卵细胞质中观察到两个或三个中期板。这些数据表明，调节第一次和第二次减数分裂进程的细胞质因子在哺乳动物卵母细胞中不是物种特异性的，并且这些因子在MII期位于减数分裂装置和/或其周围的细胞质中。
