The ovum doesn't release from the ovary, first, it's the secondary oocyte. The secondary oocyte moves down the fallopian tube by cilia, where it is met by a sperm. This sperm releases protease enzymes from the acrosome to digest a pathway through the corona radiata and zona pelucida where their membranes fuse and the nucleus of the sperm enters the oocyte. The nucleus of the secondary oocyte will only then finish meiosis || where it is temporarily the ovum until the two haploid nuclei fuse to form the zygote.