The reproductive systems are the unique organ systems in each gender that allow humans to create further generations. The male reproductive system is responsible for the production, nourishment and transport of sperm. Male reproductive structures are located both inside and outside the pelvis.

The scrotum is the pouch of skin located outside the pelvis that houses many structures of the male reproductive system. The purpose of the scrotum is to maintain the proper temperature for the production of sperm, which must be kept lower than regular body temperature. The scrotum regulates temperature by changing in size. It gets smaller and tighter when it is cold, in order to retain body heat. It gets larger and looser when it is warm, to release excess body heat.

The testicles, or testes, are the two oval-shaped organs located inside the scrotum. In an adult man, these gonads are around 2 inches (about 5 centimeters) long and about 1 inch (around 3 centimeters) wide. They normally descend from the pelvic cavity into the scrotum before birth. Structures inside the testicles called the seminiferous tubules produce sperm. The testicles are also part of the endocrine system, because they produce male sex hormones (androgens), such as testosterone.

The duct system is a series of ducts that the sperm and semen pass along between the testicles and the urethra. The epididymis is a coiled tube that connects the testicles and the vas deferens. There are two of these – one for each testicle. This is where sperm mature and are stored. The vas deferens is the tube that transports sperm-filled semen to the urethra.

The accessory glands are the organs that produce most of the fluids that make up the semen. These fluids nourish the sperm and lubricate the duct system. The seminal vesicles connect to the vas deferens, near the bladder. The prostate gland surrounds the part of the urethra below the bladder. The urethra is also part of the urinary system. It runs through the length of the penis and is the passage through which urine and semen are expelled from the body at different times.

The penis is composed of an expandable sponge-like tissue. It may vary in size and appearance greatly from one body to another, and in different developmental stages. Despite numerous advertising claims, no special exercises, diets or dietary supplements can alter the size of the penis.

The penis is composed of the shaft, glans and foreskin. The shaft is the long, cylindrical body of the penis. The glans, which is also called the head, is the cone-shaped tip of the penis. The opening of the urethra is normally located at the tip of the glans. The foreskin (prepuce) is the fold of skin that covers the glans.