Abstract
Gamete fusion, which is the final event of fertilization, is a crucial physiological event in the creation of a new fetus. In mammals, sperm IZUMO1 and oocyte IZUMO1R (JUNO) recognition play a role in triggering this process. Gamete fusion occurs through a complex but steady and unfailing intermolecular reaction because fertilization must ensure species specificity, in which fusion takes place between gametes of the same species only. Although many factors involved in this process have recently been identified, their specific contributions remain largely unknown. The current article describes detailed methods for assessment of gamete fusion in mice, visualized by fluorescent dye transfer, from unfertilized oocyte to spermatozoa. These methods are applicable not only for fixed cells but also live imaging of gametes.