Fate of the sperm mitochondria, and the incorporation, conversion, and disassembly of the sperm tail structures during bovine fertilization
Fate of the sperm mitochondria, and the incorporation, conversion, and disassembly of the sperm tail structures during bovine fertilization
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DOI：
10.1095/biolreprod55.6.1195
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发表时间：
1996-12-01
影响因子：
3.6
通讯作者：
Schatten, G
中科院分区：
文献类型：
--
作者：
Sutovsky, P;Navara, CS;Schatten, G
通过将超微结构研究与对用线粒体特异性活性染料 Mito Tracker green FM 标记的受精精子的观察相结合，探索了牛卵母细胞体外受精过程中精子的掺入以及精子衍生成分向合子结构的转化。由 Mito Tracker 标记的精子受精的受精卵在受精后的不同时间进行固定，然后进行免疫细胞化学处理，以检查 DNA、微管和精子尾部成分（包括纤维鞘和轴丝微管）的分布。我们在此表明，精子的完全掺入，而不是精子与卵母细胞的结合和卵母细胞的激活，取决于卵母细胞微丝的完整性，并受到微丝破坏剂的抑制细胞松弛素B。精子掺入后，线粒体从精子的连接部分移位，精子中心粒暴露于卵细胞质。此事件之后是基于微管的精子紫苑的形成，它负责雄性和雌性原核的结合。与此同时，精子主要部分的主要结构——纤维鞘——消失。第一次有丝分裂后，在一个卵裂球中可以看到致密的线粒体鞘。在第二次有丝分裂的入口处观察到精子线粒体的聚集，尽管它们保留在细胞核附近，并且随后可以在中期纺锤体的一极处看到。线粒体簇偶尔会在早期四细胞胚胎的一个卵裂球中发现，但在第三个有丝分裂周期开始时就不再检测到了。这些数据表明，牛受精过程中精子尾部的分解是一系列精心策划的事件，涉及特定精子结构破坏（纤维鞘和线粒体鞘）和转化（DNA、精子中心粒）到合子和胚胎成分。
Sperm incorporation and the conversion of the sperm-derived components into zygotic structures during in vitro fertilization of bovine oocytes was explored by combining ultrastructural studies with observations of the fertilizing sperm tagged with a mitochondrion-specific vital dye Mito Tracker green FM. The zygotes fertilized by the Mito Tracker-labeled sperm were fixed at various times after fertilization and then processed for immunocytochemistry to examine the distribution of DNA, microtubules, and sperm tail components, including the fibrous sheath and axonemal microtubules.We show here that the complete incorporation of the sperm, but not sperm-oocyte binding and oocyte activation, depends upon the integrity of oocyte microfilaments and is inhibited by the microfilament disrupter cytochalasin B. After sperm incorporation, the mitochondria are displaced from the sperm's connecting piece, and the sperm centriole is exposed to the egg cytoplasm. This event is followed by the formation of the microtubule-based sperm aster, which is responsible for the union of male and female pronuclei. Concomitantly, the major structure of the sperm principal piece, the fibrous sheath, disappears. After the first mitosis, the compact mitochondrial sheath can be seen in one of the blastomeres. An aggregate of the sperm mitochondria is observed at the entry of the second mitosis, although they remain in the vicinity of the nucleus and can later be seen at one pole of the metaphase spindle. The mitochondrial cluster is occasionally found in one of the blastomeres in the early-stage four-cell embryos, but it is no longer detected by the beginning of the third mitotic cycle.These data suggest that the disassembly of the sperm tail during bovine fertilization occurs as a series of precisely orchestrated events involving the destruction (fibrous sheath and mitochondrial sheath) and transformation (DNA, sperm centriole) of particular sperm structures into zygotic and embryonic components.