Role of microvesicles in sperm functions

精子是在睾丸中产生的。它们必须经过雄性和雌性的生殖道才能到达卵子附近。雄性生殖道显示出很大的变异性时，比较解剖的脊椎动物物种。进行体内受精的物种的一个特殊性是附睾。该器官由希腊语epi（意为“上”）和didymos（意为“睾丸”）组成，是一个连接睾丸和输精管的长曲小管，随后是射精管。在农场动物中，解开的附睾可以达到90米长，精子运输可能需要长达15天。已分化的雄配子在离开睾丸后不能受精，在附睾转运过程中，它将获得其可受精性和向前运动特性。这些变化统称为精子成熟。在此过程中，精子与附睾腔内隔室相互作用，其特征在于沿着附睾变化的不寻常的生化成分。附睾液依次与雄配子相互作用以改变其生化组成和性质：这些改变是精子成熟所必需的。* 多年来，我的研究一直集中在精子成熟过程中的生化修饰上。我们对脊椎动物雄性生殖生理学这一关键步骤的理解的主要贡献之一是附睾体的表征。这些微泡被分泌到附睾腔中，并在精子修饰中起主要作用。我们已经证明，附睾体的生化特性和组成沿着附睾而变化，并且它们选择性地将它们的一些蛋白质成分转移到成熟的精子中。我们正在进行的工作是了解附睾的异质性，蛋白质组成和起源。我们还想了解这些囊泡与成熟精子相互作用的分子机制。我们还将研究附睾体在精子生理参数中的作用。总之，我们的研究计划将带来新的理解精子处理的复杂过程沿着男性生殖道的脊椎动物物种。这项工作将应用于人工授精业、与繁殖物种有关的生殖技术以及濒危物种的保护。 *****

Spermatozoa are produced in the testis. They have to transit both the male and female reproductive tracts before reaching the vicinity of the egg. The male reproductive tract shows great variability when comparing the anatomy of vertebrate species. One particularity of species practicing internal fertilization is the epididymis. Formed from the Greek epi meaning «on» and didymos «testis», this organ is a long convoluted tubule linking the testis to the vas deferens followed by the ejaculatory duct. In farm animals, the unravelled epididymis can reach 90 m long and sperm transit can take as long as 15 days. The differentiated male gamete is incapable of fertilization upon leaving the testis and it is during epididymal transit that it will acquire its fertilizing ability and its forward motility properties. These modifications are collectively called sperm maturation. During this process, spermatozoa interact with the epididymal intraluminal compartment, which is characterized by an unusual biochemical composition that varies along the epididymis. The epididymal fluid interacts sequentially with the male gamete to modify its biochemical composition and properties: these modifications are necessary for sperm maturation. ***For many years, my studies have focussed on the biochemical modifications involved in sperm maturation. One of our major contributions to the understanding of this critical step in vertebrate male reproductive physiology is the characterization of epididymosomes. These microvesicles are secreted into the lumen of the epididymis and play major roles in sperm modifications. We have shown that the biochemical properties and composition of epididymosomes vary along the epididymis and that they selectively transfer some of their protein constituents to maturing spermatozoa. Our ongoing work is to understand the heterogeneity, the protein composition and the origin of epididymosomes. We also want to understand the molecular mechanisms governing interactions of these vesicles with the maturing spermatozoa. We will also investigate the role of epididymosomes in sperm physiological parameters. Altogether, our research program will bring new understanding to the complex process of sperm processing along the male reproductive tract in vertebrate species. This work will have application to the artificial insemination industry, to reproductive technologies concerned with breeding species and to endangered species preservation. *****