In vitro fertilisation. Computer artwork showing the microscopic procedure of injecting a sperm into a human egg, during the process of in vitro fertilisaton (IVF). At centre is the rounded egg. A micro-needle (at right, green) has penetrated the egg and is injecting a single sperm cell. At left, a flat-nosed pipette is used to hold the egg steady while the needle is inserted. This technique ensures penetration and fertilisation of the egg, without wasting millions of sperm. It is a specialized technique which has been used successfully at IVF centres around the world, for the treatment of certain infertility problems.