Fusion of Sperm and EggThe obtained oocyte and the prepared semen sample are placed in a dish to enable fertilization under artificial conditions (insemination). This happens at the end of 14- 26 hours after insemination. Many embryos are allowed to develop. If fertilization occurs, the resultant cell (zygote) cleaves to form two, four and eight cells over several days. Published on May 06, 2014Last Updated on Feb 24, 2020