Intracytoplasmic Sperm Injection (ICSI) is the process of injecting a sperm into a mature oocyte (egg). The sperm is chosen based on how normal it appears. The sperm is picked up using a microinjection needle and injected into the oocyte. Once the needle enters the egg, suction is applied to make sure the oocyte membrane has been penetrated. Once this has been verified, the needle is pushed slightly forward and the sperm is deposited inside the oocyte.