vēˈtrō, vĭˈtrō, 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. If fertilization occurs, a fertilized ovum, 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 can also now be frozen and fertilized later.

First developed by Drs. 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 now used to enable prospective parents with other reproductive problems (e.g., inability to produce eggs, poor sperm quality, or endometriosis) to bear a child. The technique has raised legal, ethical, and religious issues, including concerns regarding legal custody of frozen embryos following divorce. 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.

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

See L. Andrews, The Clone Age (1999).

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