MODEL RELEASED. In vitro fertilisation (IVF) being performed by a fertility doctor (right). The doctor is using a light microscope to view a human egg cell (seen on screen at left). The egg cell (centre of screen) is being held in place by a micro-pipette (left), as a micro-needle (right) is used to inject a human sperm cell inside the egg cell. This is known as intracytoplasmic sperm injection (ICSI). The injected sperm fertilises the egg and the resulting zygote is grown in the laboratory until it reaches an early stage of embryonic development. It is then placed in the patient's uterus to develop into a foetus. IVF allows infertile couples to conceive a child.