Van Blerkom J, Davis P W, Merriam J
Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder 80309.
Hum Reprod. 1994 Apr;9(4):697-708. doi: 10.1093/oxfordjournals.humrep.a138574.
This study demonstrates that sperm penetration into the ooplasm occurs at high frequency in germinal vesicle (GV) stage human oocytes which failed to resume meiosis after ovulation induction in cycles of ovarian hyperstimulation for in-vitro fertilization. The capacity of the immature human oocyte to prevent polyspermic penetration at the cell surface level was suggested by the finding that despite the presence of numerous spermatozoa within the zona pellucida and on the oocyte surface within 3 h after insemination, all normal-appearing GV stage oocytes examined in this study were penetrated by a single spermatozoon. This notion was also supported by scanning confocal microscopic analysis of oocytes double-stained for DNA and cortical granules which showed highly localized regions of cortical granule-free cytoplasm in proximity to the penetrated spermatozoon. The developmental ability of these oocytes was assessed by culture in vitro. The results show that oocytes penetrated by a spermatozoon at the GV stage resume meiosis, develop the capacity to decondense sperm DNA, abstrict both first and second polar bodies, and form a male pronucleus from the spermatozoon which enters the oocyte prior to the resumption of meiotic maturation. After penetration, sperm nuclei rapidly migrate to the centre of the oocyte and become juxtaposed with the germinal vesicle, suggesting the presence of a cellular mechanism which permits directed movement within the cytoplasm. The developmental ability of these oocytes and the normality of the resulting embryos are discussed.
本研究表明，在体外受精的卵巢过度刺激周期中，经排卵诱导后未能恢复减数分裂的生发泡（GV）期人类卵母细胞中，精子穿透卵质的情况高频发生。尽管在授精后3小时内透明带内和卵母细胞表面存在大量精子，但本研究中检查的所有外观正常的GV期卵母细胞均被单个精子穿透，这一发现提示未成熟人类卵母细胞在细胞表面水平具有防止多精受精的能力。对DNA和皮质颗粒进行双重染色的卵母细胞进行扫描共聚焦显微镜分析也支持了这一观点，该分析显示在穿透精子附近存在高度局限的无皮质颗粒细胞质区域。通过体外培养评估这些卵母细胞的发育能力。结果显示，在GV期被精子穿透的卵母细胞恢复减数分裂，形成使精子DNA解聚的能力，排出第一极体和第二极体，并由在减数分裂成熟恢复之前进入卵母细胞的精子形成雄原核。穿透后，精子核迅速迁移至卵母细胞中心并与生发泡并列，这表明存在一种允许在细胞质内定向移动的细胞机制。本文讨论了这些卵母细胞的发育能力以及所产生胚胎的正常性。
