The choreography of fertilization

Abstract

At fertilization, a continuum is established between the final phases of oogenesis and the formation of a new individual. In mammals, the two processes are overlapped. The fertilizing spermatozoon represents the paternal contribution to zygote constitution and at the same time the trigger for the completion of meiosis. Oocytes can mimic fertilization, being able to recapitulate autonomously many of the events of early embryonic development. However, without the sperm contribution development to term cannot occur. The sperm, in fact, carries not only the paternal chromosomes, but also cytoskeletal elements and biochemical cues that are essential to complement and regulate the oocyte cellular legacy. Therefore, oocyte-sperm fusion creates a unique cellular machinery whose regulation in time and space influences the long term destiny of the ensuing embryo.