Bouchard P, Cosson M P
Ann Endocrinol (Paris). 1981 Oct-Nov;42(4-5):398-406.
Sperm flagella like somatic cilia consist of an axoneme of 9 + 2 microtubules. Several projections protrude form the A subfiber of each microtubule doublets: the 2 rows of Dynein arms, the Radial Spokes and the Nexin Links. All the axonemal components constitute the flagellar motor. The energy necessary to generate microtubule sliding, responsible of the flagellar beat, is provided by Mg2+-ATP hydrolysis by Dynein ATPase. The Dynein ATPase is a group microtubule A called Dynein arms. Mg2+-ATP binding and hydrolysis generate transient cross-bridges that cause the microtubule doublets walk one upon another. The transformation of sliding to bending is produced by the Radial Spokes which eventually go through a cycle of transient attachment to the central sheath. The flagellar movement is controlled by intra-flagellar factors mostly Ca2+, responsible for the symmetry of the beat and the arrest of flagellar motility. Further, cAMP increase is associated in certain conditions with the initiation or increase of sperm motility. Extrinsic factors seem to play a major role in the control of sperm motility, such as proteins that coat the sperm membrane or factors associated with the egg, like the peptide "speract", extracted from sea urchin egg, which stimulates sperm respiration rate and increases cAMP and cGMP concentrations.
精子鞭毛与体细胞纤毛一样，由9 + 2微管组成的轴丝构成。每个微管二联体的A亚纤维伸出几个突起：两排动力蛋白臂、辐条和连接蛋白连接。所有轴丝成分构成鞭毛运动器。产生鞭毛摆动所必需的微管滑动的能量由动力蛋白ATP酶水解Mg2 + -ATP提供。动力蛋白ATP酶是一组称为动力蛋白臂的微管A。Mg2 + -ATP结合和水解产生瞬时交叉桥，导致微管二联体相互移动。滑动向弯曲的转变由辐条产生，辐条最终经历与中央鞘的瞬时附着循环。鞭毛运动由鞭毛内因子控制，主要是Ca2 +，负责摆动的对称性和鞭毛运动的停止。此外，在某些情况下，cAMP增加与精子运动的启动或增加有关。外在因素似乎在精子运动的控制中起主要作用，例如覆盖精子膜的蛋白质或与卵子相关的因素，如从海胆卵中提取的肽“精子活化肽”，它刺激精子呼吸速率并增加cAMP和cGMP浓度。
