Molecular mechanisms leading to gamete fusion.

The fusion between spermatozoon and oocyte represents the final stage of fertilization in mammals.　Since only one of the extremely large number of spermatozoa fertilizes the oocyte, there should be a strictly regulated molecular mechanism in gamete fusion.　Oocyte CD9 was first identified as a key factor for gamete fusion, followed by sperm IZUMO1 and oocyte IZUMO1 receptor JUNO. Since 2020, with the recent emergence of genome editing technologies, new gamete fusion sperm factors, SPACA6, TMEM95, FIMP, SOF1, DCST1, and DCST2, have been reported one after another.　In this review, I would like to give an overview of mammalian gamete fusion based on the latest findings on these factors.