Abstract: The initiation and activation of sperm function is a complex process, involving multiple signaling molecules and pathways. Sperm undergo the activation in epididymis after generated in testis and the hyperactivation in female reproductive tract, which is a prerequisite for sperm capacitation. Subsequently, spermatozoa achieve capacitation under the mediations of cAMP-PKA, ERK-MAPK, endocannabinoid and other pathways, and quickly move to the egg. At this point, the acrosomal reaction starts, and a complex cascade of signaling pathways mediates the fusion of membrane and the release of acrosomal enzymes, in which sperm cross the cumulus interstitial and zona pellucida. The sperm recognize and bind the proteins on the membrane surface of the egg after successfully entered the perioocyte space. With the assistance of heat shock protein, sperm equatorial segment proteins, cysteine-rich secretory proteins and some protein pairs such as ADAM-Integrin, Izumo1-Juno, the sperm-egg fusion was completed. In this paper, we reviewed the mechanisms of sperm capacitation, acrosomal reaction and fertilization.

Key words: Spermatozoa；, Sperm function；, Hyperactivation；, Sperm capacitation；, Acrosome reaction；, Fertilization；, Sperm motility