For fertilization of the ovum and subsequent development of an embryo to occur, the head of the sperm must cross the ovule wall. Alterations in sperm can make this task not possible.
Intracytoplasmic sperm injection (ICSI) allows this dysfunction to be corrected by injecting the sperm directly into the cytoplasm of the ovule, this procedure is known as in vitro fertilization ICSI. Once the embryo is developed, the process is the same as conventional In Vitro Fertilization.