Most fertilizing mouse spermatozoa begin their acrosome reaction before contact with the zona pellucida during in vitro fertilization
Most fertilizing mouse spermatozoa begin their acrosome reaction before contact with the zona pellucida during in vitro fertilization
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DOI：
10.1073/pnas.1018202108
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发表时间：
2011-03-22
影响因子：
11.1
通讯作者：
Hirohashi, Noritaka
中科院分区：
文献类型：
--
作者：
Jin, Mayuko;Fujiwara, Eiji;Hirohashi, Noritaka
真兽类的精子要与卵母细胞融合，必须穿过细胞外衣、卵丘细胞层和透明带(ZP)。精子顶体反应(AR)是精子穿透透明带并与卵母细胞融合所必需的，通常认为是由精子与透明带接触引起的。因此，在之前对小鼠精子-卵母细胞相互作用的大多数研究中，为了便于检查精子-小带相互作用，在受精前去除了卵丘。我们使用转基因小鼠精子，这使我们能够使用荧光显微镜检测顶体反应的开始。我们发现，在到达卵带之前开始顶体反应的精子能够穿透卵带并与卵母细胞的质膜融合。事实上，大多数受精的精子在到达卵丘包裹的卵母细胞的透明带之前都经历了顶体反应，至少在我们使用的实验条件下是这样。卵丘细胞与卵丘细胞共孵育可提高去卵丘卵母细胞的体外受精率，提示卵丘细胞及其基质在自然受精中具有重要作用。
To fuse with oocytes, spermatozoa of eutherian mammals must pass through extracellular coats, the cumulus cell layer, and the zona pellucida (ZP). It is generally believed that the acrosome reaction (AR) of spermatozoa, essential for zona penetration and fusion with oocytes, is triggered by sperm contact with the zona pellucida. Therefore, in most previous studies of sperm-oocyte interactions in the mouse, the cumulus has been removed before insemination to facilitate the examination of sperm-zona interactions. We used transgenic mouse spermatozoa, which enabled us to detect the onset of the acrosome reaction using fluorescence microscopy. We found that the spermatozoa that began the acrosome reaction before reaching the zona were able to penetrate the zona and fused with the oocyte's plasma membrane. In fact, most fertilizing spermatozoa underwent the acrosome reaction before reaching the zona pellucida of cumulus-enclosed oocytes, at least under the experimental conditions we used. The incidence of in vitro fertilization of cumulus-free oocytes was increased by coincubating oocytes with cumulus cells, suggesting an important role for cumulus cells and their matrix in natural fertilization.