The document describes the male and female reproductive systems. The male system includes the testes, sperm duct, prostate, urethra and penis which work together to produce and release sperm. The female system includes the ovaries, oviducts, uterus, cervix and vagina which work to produce and release eggs, allow fertilization to occur and support fetal development. Fertilization happens when a single sperm meets and enters an egg in the oviduct, joining their nuclei to form a fertilized egg or zygote.