Reproduction’s organs differ by sex more than most body systems
The reproductive—or genital—system gathers organs for sexual or asexual reproduction, aided by fluids, hormones, and pheromones. In mammals that means external genitals plus gonads; vertebrates share gonads, ducts, and openings yet invent wildly different strategies. Human STIs keep the system a public-health front line.
The reproductive, or genital, system is every organ an organism uses to reproduce, whether sexually or asexually, together with supporting substances such as fluids, hormones and pheromones. It is unusual among organ systems in how much it differs between the sexes of one species. Those differences are what allow two parents to mix their genes, which can give offspring greater genetic fitness.
In mammals the main parts are the external genitalia, the penis and vulva, and internal organs including the gonads, the testicles and ovaries that make gametes. Most other vertebrates follow a similar layout of gonads, ducts and openings. In females the gonads connect through oviducts to an outside opening, usually a cloaca or vagina. Around that shared plan, every vertebrate group has evolved a wide range of body adaptations and breeding strategies.
The female system has two jobs: making egg cells, and protecting and feeding the offspring until birth. Its three main parts are the vulva leading to the vagina, the uterus that holds the developing fetus, and the ovaries that produce eggs; breasts matter after birth but are usually classed separately. The male system has one job, producing and delivering sperm. The testicles make sperm inside the temperature-regulating scrotum, and the epididymides store and mature it. The seminal vesicles and prostate add fluid, and the penis and urethra deliver it. Testosterone, the key male androgen, drives sperm development and traits such as facial hair and a deeper voice.
Human fertilisation happens inside the body. Sperm swim past the cervix into the uterus or on into the fallopian tubes, where fertilisation can occur, and after implantation the fetus develops for about nine months. Birth comes as the uterine muscles contract and the cervix widens. Human infants then need long parental care, including milk from the mammary glands. Diseases of this system are widespread, especially sexually transmitted infections.
Source: Reproductive system
