Re: How are eggs retrieved from human females prior to in vitro fertilization?

It isn't easy. Human ovaries (as with all vertebrates) are found inside the female body cavity, so getting to the eggs requires some form of surgery. But humans don't go into estrus, so there are no clear signals indicating that their eggs are mature and ready to be removed for in vitro fertilization (IVF). To make the proccedure even more complicated, humans generally only produce one or two mature eggs in any given cycle.

So doctors begin the process of IVF by treating women with "ovarian stimulation medications." These contain large doses of the same hormones that normally control a woman's fertility. Large amounts of follicle stimulating hormone (FSH) make the ovaries produce many mature eggs at once; this in turn increases the chances that one egg will survive retrieval, get fertilized, and implant in the uterus to produce a pregnancy. Once the eggs are mature, a second hormone -- human chorionic gonadotropin (hCG ) -- is used to stimulate the release of the eggs. The patient is monitored with ultrasound and blood tests to indicate when egg retrieval can begin.

There are two ways to remove eggs from the ovary: ultrasound-guided aspiration or laparoscopy. In either case, the woman is put under general anesthesia. In ultrasound-guided aspiration, ultrasound is used to get an image of the ovary, and a needle is passed through the woman's abdominal wall directly into each mature follicle to remove an egg. In laparoscopy, the physician inserts a surgical instrument called a laparoscope into the woman's abdominal cavity. The laparoscope uses an aspiration system to produce light suction that removes the egg from its follicle.

Reference: Gilbert, S. F. Developmental Biology 6th edition. Sinauer Associates: Sunderland, MA
Or check out this web page: http://www.fertilitext.org/

Diane A. Kelly, Ph. D.
Visiting Assistant Professor
Mount Holyoke College
Department of Biological Sciences