IVF embryo bank. Technician retrieving frozen embryos from an in vitro fertilization (IVF) embryo bank. They are stored in liquid nitrogen at -196 degrees Celsius. They were created by removing eggs from a woman's ovaries, fertilizing them with sperm and allowing the resulting zygotes to develop into immature embryos. These are frozen 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.