egg gamete unfertilized egg Egg that has not yet been fertilized by a sperm. An oocyte becomes an egg when it leaves the ovary by ovulation (Qazi et al., 2003). Ovulation triggers egg activation, which alters envelope permeability and causes the resumption of meiosis and translation (Qazi et al., 2003). oocyte fly_anatomy.ontology FBbt:00015288