Whitfield Marjorie
Institute for Advanced Biosciences, INSERM U 1209, CNRS UMR 5309, Université Grenoble Alpes, Team 'Physiopathology and Pathophysiology of Sperm cells', 38000, Grenoble, France.
Basic Clin Androl. 2024 Dec 16;34(1):25. doi: 10.1186/s12610-024-00241-2.
The annulus is an electron-dense ring structure that surrounds the axoneme and compartmentalizes the sperm flagellum into two parts: the midpiece and the principal piece. The function of the annulus as a diffusion barrier in the mature spermatozoon is now well described but its function during spermiogenesis remains unclear. The intriguing spatio-temporal dynamics of the annulus during spermiogenesis and its position at the interface of the two main flagellar compartments have been highlighted for more than 50 years, and suggest a major role in this process. During the last decade, numerous studies contributed in establishing a repertoire of proteins known to be located at the annulus. Mutant mouse models of invalidation of these proteins have provided essential information and clues for novel hypotheses regarding the functions and regulation of this structure. Importantly, the recent identification in humans of homozygous mutations of genes coding for annulus proteins and leading to sterility have reinforced the importance of this ring structure for sperm physiology and male fertility. This review provides a comprehensive description of all the knowledge obtained in the last several years regarding the annulus composition and functions, both in mice and in humans.
环是一种电子致密的环形结构，围绕着轴丝，并将精子鞭毛分为两部分：中段和主段。环在成熟精子中作为扩散屏障的功能现已得到充分描述，但其在精子发生过程中的功能仍不清楚。在精子发生过程中环有趣的时空动态及其在两个主要鞭毛区室界面处的位置已被关注了50多年，这表明它在这个过程中起主要作用。在过去十年中，大量研究致力于确定已知位于环上的蛋白质清单。这些蛋白质缺失的突变小鼠模型为有关该结构的功能和调控的新假说提供了重要信息和线索。重要的是，最近在人类中鉴定出编码环蛋白的基因的纯合突变并导致不育，这进一步强调了这种环形结构对精子生理和男性生育能力的重要性。本综述全面描述了过去几年在小鼠和人类中获得的关于环的组成和功能的所有知识。
