Some of the 'hot' red squares in this graphic are active - The CD-Rom "An Introduction to Assisted Reproduction" from the IFC Resource centre provides a more extended discussion.
In conception as a result of sexual intercourse the egg and sperm
usually meet high up in the fallopian tube. If fertilisation does takes place,
the fertilized egg develops into an embryo and moves down the fallopian tube
towards the uterus - by the time it reaches the uterus it is ready to implant
in the endometrium which has thickened ready to receive the embryo. It is the
embryo which initiates the implantation process and it is known that between
50% & 70% of embryos never do implant - there is a tremendous natural
wastage.
In IVF the fertilisation and early embryo development takes
place in the laboratory (in culture medium). Embryos are transferred to the
uterus during embryo transfer at the early cleavage stages or, with the
development of new culture techniques, at the blastocyst stages.
One
in six couples have difficulties in having a baby and may seek help through
assisted reproductive medicine. In GIFT the sperm & eggs are transferred to
the fallopian tubes so that fertilisation takes place within the body and the
embryos can benefit from the natural secretions and contact with the cells of
the fallopian tubes & upper uterus. In Artificial insemination sperm may be
placed at the top of the vagina as semen or (as a culture of cells) within the
cervical canal or directly into the uterus.
See also follicular stimulation.