Illustration of an IVF (In Vitro Fertilization). On the left, a classic IVF: the spermatozoa and occytes are placed in an embryo culture environment that favors their survival. Spontaneous fertilization takes place at 37?during incubation. On the right: IVF ICSI: having taken and prepared the sperm and ovules in a favorable embryo culture environment, a spermatozoon is injected into the ovule cytoplasm. After a 48-hour incubation period, the fertilized egg becomes an embryo which can be transferred to the uterus. Several embryos are be obtained, two or three of which will be transferred to the uterus. The others are frozen and transferred later if the couple so wishes.