In vitro fertilization

In certain forms of infertility, in vitro fertilization (IVF) can assist people to have a child. Follicle growth in the ovary is stimulated with gonadotrophins. Shortly before ovulation, oocytes are collected through aspiration from the ovarian follicles and held in a culture medium. Spermatozoa are then added into the medium to fertilize the oocytes. The resulting embryos are allowed to develop up to the 8-cell or blastocyst stage. They are then implanted into the uterus (embryo transfer), where they penetrate the epithelium.
Intracytoplasmic sperm injection (ICSI) differs from IVF in that only one spermatozoon is injected into the oocyte. This method is used when sperms are unable to penetrate the oocyte.