The syngamy is the sexué process of fusion of two Gamète S, a male and a female, to form a Zygote. This process starts with the fusion of the external membranes in order to form a unicellular entity Diploïde, the zygote. Although the Karyogamie can not start immediately, the zygote thus formed cannot be any more fertilized by the male gamètes which would cross it.