以前普遍认为，精子中的线粒体DNA之所以没能遗传下来，是因为在受精时只有精子头部（不含线粒体）进入卵子，而含线粒体的中部（称为线粒体鞘）被排除在外。1996年有两项研究发现这种曾被普遍接受的观点并不准确。在受精时，精子的线粒体鞘也进入了卵子，但是在随后的两次细胞分裂中，精子线粒体消失。所以受精卵中的线粒体完全来自卵子，但我前面说的“在受精时只有精子头部进入卵子，而精子头部不含线粒体”是过时观点，应该删去。
附文献：
Proc Natl Acad Sci U S A. 1996 Nov 26;93(24):13859-63.
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Misconceptions about mitochondria and mammalian fertilization: implications for theories on human evolution.
Ankel-Simons F, Cummins JM.
Duke University Primate Center, Durham, NC 27705, USA.
In vertebrates, inheritance of mitochondria is thought to be predominantly maternal, and mitochondrial DNA analysis has become a standard taxonomic tool. In accordance with the prevailing view of strict maternal inheritance, many sources assert that during fertilization, the sperm tail, with its mitochondria, gets excluded from the embryo. This is incorrect. In the majority of mammals-including humans-the midpiece mitochondria can be identified in the embryo even though their ultimate fate is unknown. The "missing mitochondria" story seems to have survived--and proliferated-unchallenged in a time of contention between hypotheses of human origins, because it supports the "African Eve" model of recent radiation of Homo sapiens out of Africa. We will discuss the infiltration of this mistake into concepts of mitochondrial inheritance and human evolution.
PMID: 8943026 [pubmed - indexed for medline]
PMCID: PMC19448
Biol Reprod. 1996 Dec;55(6):1195-205.
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Fate of the sperm mitochondria, and the incorporation, conversion, and disassembly of the sperm tail structures during bovine fertilization.
Sutovsky P, Navara CS, Schatten G.
Department of Zoology, University of Wisconsin, Madison 53706, USA.
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 MitoTracker green FM. The zygotes fertilized by the MitoTracker-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.
Publication Types:
" Research Support, U.S. Gov't, Non-P.H.S.
" Research Support, U.S. Gov't, P.H.S.
PMID: 8949874 [pubmed - indexed for medline]