Fertilization target refers to the EGG or OVUM that is the intended recipient of a sperm cell during fertilization. The EGG, which has three letters in its spelling, is the female reproductive cell that is released from the ovary and is capable of being fertilized by a sperm cell. The OVUM, which has four letters in its spelling, is the mature female reproductive cell that is released from the ovary and is capable of being fertilized by a sperm cell. Both the EGG and OVUM are necessary for successful fertilization.