Sperm cell: Sperm cells are the male reproductive cells that are produced by most animals. Sperm cells are, generally, motile and make use of a "whip like" tail to navigate and penetrate an ovum, or egg cell. During reproduction, the main goal of a sperm cell is to fertilize the ovum. Once fertilized, the sperm and ovum form a new offspring that will contain 23 chromosomes form the sperm and 23 chromosomes form the ovum.