Sperm cells travel from the testis through the vas deferens, seminal vesicles, urethra and penis. Upon ejaculation, sperm enter the female's vagina and cervix on the way to fertilizing an egg in the ovary. The male reproductive system includes structures like the testis, vas deferens and penis that produce, store and transport sperm. The female system includes ovaries that hold eggs, and a uterus where fertilization and fetal development may occur if pregnancy is achieved.