2009 Volume 44 Issue 2 Pages 117-120
Spermatozoa are specialized for transport of genome and egg-activating factors. It is important to understand the structural molecular basis of sperm flagella to comprehend sperm movement. In addition to axoneme, flagella of mammalian spermatozoa have a peri-axonemal structure composed of accessory structures, such as outer dense fibers, fibrous sheath, satellite fibrils, mitochondrial sheath, which is connected to axoneme in flagella. Its structure is more complex than that of lower vertebrates that lacks the accessory structures. Recent progress in identification and analyses of the molecules consisting of sperm flagella provides important information for understanding the mechanisms of sperm flagella movement. We here outline advances of recent researches concerning the structures and functions of the accessory structures in mammalian sperm flagella.