The most common procedure is called In Vitro Fertilization (IVF). This is a technique often used nowadays to treat fertility problems in sterile couples and consists of cultivating the eggs obtained from the donor with semen from the recipientís partner in a special laboratory environment.
Later, the embryos obtained are transferred to the interior of the recipientís uterus where they will continue their growth if the implantation is successful. Normally, two or three are transferred, because usually only one takes and, all being well, will continue its gestation there.
When there are also problems associated with the man (as is the case of scarce semen) a complementary technique can also be used called Intracytoplasmic Sperm Injection (ICSI). This consists of a very fine microscopic manipulation technique where the sperm is manually injected into the interior of the egg. This egg, once fertilized, is the one which is transferred, as in the previous case, into the recipientís uterus.