in vitro fertilization

in vitro fertilization , technique for conception of a human embryo outside the mother's body. Several ova , or eggs, are removed from the mother's body and placed in special laboratory culture dishes (Petri dishes); sperm from the father are then added, or in many cases a sperm is injected directly into an ovum, a process known as intracytoplasmic sperm injection. If fertilization is successful, a fertilized ovum (or several fertilized ova), after undergoing several cell divisions, is either transferred to the mother's or a surrogate mother's body for normal development in the uterus, or frozen for later implantation. Eggs also can be frozen and fertilized later. In vitro maturation is when the ova are extracted and then matured in a laboratory (instead of in the mother's body) before they are fertilized.

First developed by Patrick C. Steptoe and Robert G. Edwards of Great Britain (where the first "test-tube baby" was born under their care in 1978), the technique was devised for use in cases of infertility when the woman's fallopian tubes are damaged or the man's sperm count is low. It is also used to enable prospective parents with other reproductive problems (e.g., inability to produce eggs, poor sperm quality, or endometriosis ) to bear a child, and can be used in conjunction with embryo biopsy , or preimplantation genetic diagnosis, to enable parents to have a child who is free of some inheritable defects or diseases. In embryo donation (also called embryo adoption), frozen embryos that are not needed by the mother are donated for implantation to a woman or couple who are infertile but wish to have, and are capable of bearing, children. The use of in vitro fertilization has resulted in the birth of more than a million babies. Nevertheless, the technique has raised legal, ethical, and religious issues, including concerns regarding legal custody of frozen embryos following divorce and questions regarding the appropriateness of the procedure posed by the Roman Catholic Church and other institutions.

See also artificial insemination ; fertilization ; reproductive system ; surrogate mother .

Bibliography: See L. Andrews, The Clone Age (1999); R. M. Henig, Pandora's Baby (2004).

in vitro fertilization (IVF) Fertilization of ova by sperm outside the body, in a ‘test-tube’ environment. The last resort in the treatment of infertility. Ova are removed from the woman's ovary after preparation with hormone treatment, which stimulates the maturation of several ova at the same time, rather than the usual one per month. The ova are then exposed to seminal fluid. Fertilization may be successful in some of the ova, and some of the fertilized ova may proceed through the normal first stages of cell division. The resulting embryos are observed during these earliest cell divisions before ‘good’ embryos (usually up to three) are transferred into the uterus. One or more of these embryos may successfully implant. The likelihood of achieving pregnancy is very variable — perhaps one in ten such attempts. Spare embryos may be frozen for repeated attempts. A more sophisticated technique attained in the 1990s is ‘ICSI’ — intracytoplasmic sperm injection — in which a single chosen sperm is directly inserted into an ovum, leaving still less to chance. There are reports that this can be successful even with non-motile sperm, which could never make the in vivo journey on their own.

Stuart Judge

in vitro fertilization (IVF) n. fertilization of an ovum outside the body, a technique used in women with infertility and also for purposes of surrogacy and egg donation. The woman is given hormone therapy causing a number of ova to mature at the same time (see superovulation). Several of them are then removed from the ovary through a laparoscope. The ova are mixed with spermatozoa and incubated in a culture medium until the blastocyst is formed. The blastocyst is then implanted in the mother's uterus and the pregnancy allowed to continue normally.