In vitro fertilisation. Computer artwork showing the microscopic procedure of injecting the DNA of a sperm into a human egg, during the process of in vitro fertilisaton (IVF). At centre is the rounded egg. A strand of spiral DNA genetic material from a single sperm cell is entering the egg, usually injected through a micro-needle. At left, a flat- nosed pipette is used to hold the egg steady while the DNA 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.