IVF embryo bank. Technician loading a straw containing an embryo into a holder to prepare it for cryostorage. The embryo was created by in vitro fertilization (IVF). In IVF, eggs taken from a woman's ovaries are fertilized with sperm in the laboratory. The resulting zygotes are allowed to develop into immature embryos. The embryos are stored in liquid nitrogen (at -196 degrees Celsius) in case the next stage of IVF treatment, the implantation of embryos into the woman's uterus, does not result in pregnancy. Frozen embryos can then be removed from storage and the implantation process repeated. IVF treatment helps couples with infertility problems to conceive.