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The acrosome of eutherian mammals

机译：Eutherian哺乳动物的顶体

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The acrosome is not just a bag of enzymes, most of which, if not all, are singly non-essential for sperm-oocyte interaction. The Golgi-derived acrosomal cap reveals some extraordinary development and structure particularities. The acrosome of eutherian spermatozoa basically consists of two parts, the anterior and equatorial segments; the present review is devoted to the former, the initial actor in fertilization. Its occasional fanciful morphological changes during epididymal maturation are analyzed, together with its heterogeneous contents: enzymes, zona binding proteins, structural proteins (matrix) and yet to be chemically characterized crystalloids. The plasma and acrosomal membranes present stabilized ordered domains, whereas glycoprotein-free areas appear during capacitation and before fusion. Exocytosis, induced by the cumulus oophorus and/or the zona pellucida, may generally start proximally and progress anteriorly, resulting in the detachment of a hybrid membrane shroud, whose entity is probably maintained by the bound matrix. Immediately released soluble enzymes must be active during the first interactions of the gametes, whereas other lysins, bound to the matrix or stored as proenzymes, are only progressively released. Zona binding is probably achieved via the shroud and/or the IAM (depending on species). Penetration along an incurved slit through the stratified zona is allowed by the rigid and denuded head tip and flagellar hyperactivity, and assisted by the local proteolytic activity of proteasomes bound to the IAM, the unique essential zona lysin system.
机译：顶体不仅是一袋酶，大多数（如果不是全部的话）对于精卵细胞的相互作用根本不是必需的。高尔基体的顶体帽揭示了一些非凡的发育和结构特性。真精子的顶体基本上由前部分和赤道部分两部分组成。目前的审查是针对前者，即受精的最初参与者。分析了其在附睾成熟过程中偶尔发生的奇异形态变化，以及其异质含量：酶，透明带结合蛋白，结构蛋白（基质）以及尚待化学鉴定的晶体。质膜和顶体膜呈现稳定的有序结构域，而在获能期间和融合前出现无糖蛋白的区域。由卵丘和/或透明带引起的胞吐作用通常可能从近端开始并向前发展，从而导致杂化膜覆盖物脱离，杂物膜覆盖物可能由结合的基质维持。立即释放的可溶性酶必须在配子的第一次相互作用中具有活性，而与基质结合或作为酶原存储的其他溶菌素只能逐步释放。透明带结合可能是通过覆盖物和/或IAM（取决于物种）实现的。坚硬且裸露的头顶和鞭毛过度活跃，允许沿着弯曲的缝隙穿透分层的透明带，而蛋白酶体与IAM（独特的基本透明带溶素系统）结合的局部蛋白水解活性则可以帮助穿透。

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