For the sake of simplicity, the male reproductive system can be divided into internal and external parts. Externally, the system consists of the penis and the scrotum. Within the scrotum, there are the testicles, the epididymis, and the vans deferens. Other internal parts of the male reproductive system include the prostate gland, the bulbourethral glands, and the urethra.
The penis is one of the most recognized parts of the male reproductive system, and it has two primary parts. The glans, or the head of the penis, is a part that is believed to significantly contribute to the pleasure of a sexual experience, and it contains the urinary meatus, which is an opening that allows urine and semen to escape the body. The second part of the penis is the shaft, which is the cylindrical portion of the penis that stiffens and lengthens during sexual arousal.
Below the penis is a sac-like structure referred to as the scrotum. It contains two oval-shaped parts known as the testicles, which are responsible for the production and storage of sperm and the production of testosterone. The scrotum also houses the epididymis and vans deferens, which act as a piping network for the male reproductive system. Another important function of the scrotum is that, through expansion and contraction, it helps to regulate the temperature of the testicles by exposing them to more or less body heat.
Seminal vesicles are located near the base of the bladder. These small sac-like structures connect to the vans deferens. The majority of the seminal fluid is produced by these structures. Its contribution is fructose-rich and thus provides the sperm with fuel that it needs to be mobile.
The prostate gland is an internal part of the male reproductive system. It is located beneath the bladder and plays a role in the production of semen by contributing fluids that nourish the sperm. The urethra is a passageway that carries urine from the bladder to the urinary meatus. This passageway, which travels through the prostate gland, also carries semen. The urethra is structured so that it does not allow the mixing or simultaneous transport of semen and urine.
At the sides of the urethra are the bulbourethral glands, sometimes referred to as Cowper's glands. These structures produce a clear fluid that often secretes from the penis during periods when a man is sexual aroused but preceding any ejaculation. The fact that fluid is produced before ejaculation is significant, because it is believed that one of its purposes is to serve as a lubricant. As it drains into the urethra, it is also believed to neutralize the acidity that may result from urine.