Prostate Gland

The prostate (not prostrate) is a small, rubbery gland about the size of a ping-pong ball, located deep inside the groin, between the base of the penis and the rectum. It is important for reproduction, because it supplies part of the seminal fluid (semen), which mixes with sperm from the testes. Seminal fluid helps the sperm to travel and survive.

The more you know about the prostate, its normal development and function, where it’s located, and what it’s attached to, the better you can understand how prostate cancer develops and impacts a man’s life over time—due either to cancer growth, or as a result of treatments.

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The prostate sits deep inside the groin.

The seminal vesicles are rabbit-eared structures that sit on top of the prostate and store and secrete a large portion of the ejaculate.

The neurovascular bundle is a collection of nerves and blood vessels that run along each side of the prostate, and helps to control erectile function. In some men, these nerves run a short distance away from the prostate, but in others, they attach to the prostate itself. Their precise location doesn’t impact prostate function or contribute to prostate cancer when it occurs.

The bladder is like a balloon that gets larger as it fills with urine. The urethra, a narrow tube that connects to the bladder, runs through the middle of the prostate and along the length of the penis, carrying both urine and semen out of the body. It is the hose that drains the bladder.

The rectum, which sits right behind the prostate, is the lower end of the intestines and connects to the anus.

Prostate Zones

The prostate is divided into several anatomic regions, or zones. Most prostate cancer starts in the peripheral zone (the back of the prostate), near the rectum. That’s why a digital rectal exam (DRE), in which a doctor examines the prostate by inserting a gloved finger in the rectum, is a common and useful screening test in addition to the PSA blood test.

Difficulty with urination is usually not a symptom of prostate cancer. In most cases, lower urinary tract symptoms are due to Benign Prostatic Hypertrophy (BPH), which is a non-cancerous prostate condition that typically develops from the transition zone that surrounds the urethra, or urinary tube (closer to the middle of the prostate).

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What Does the Prostate Do?

The prostate is not essential for life, but it is important for reproduction. Healthy semen is the perfect consistency and environment for sperm transit and survival, and for fertilization. Semen includes enzymes like PSA (which is often measured as part of screening for prostate cancer), as well as other substances made by the seminal vesicles and prostate, such as zinc, citrate, and fructose (that actually gives sperm energy to make the journey to the egg). Semen also contains substances that may protect the urinary tract and sperm from bacteria and other pathogens.

The prostate typically grows during adolescence, under the control of the male hormone testosterone and its byproduct dihydrotestosterone (DHT). Testosterone is primarily made in the testes, but a smaller amount it is also made in the adrenal glands above the kidneys.