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The prostate (or prostate gland) is part of a man’s reproductive and urinary systems. It is about the size of a walnut in younger men, but it starts to get larger when men reach their late 40s and early 50s.
The prostate is deep inside a man’s pelvis, below the bladder and in front of the rectum. It wraps around the upper part of the urethra (called the prostatic urethra). The urethra is a tube that carries urine from the bladder, through the prostate and penis, and out of the body.
The prostate is close to parts of the digestive, urinary and reproductive systems. As a result, prostate cancer and its treatments can affect these systems. For example, an enlarged prostate can press on and block the urethra, which can cause problems urinating. Radiation therapy for prostate cancer can affect the rectum and cause bowel problems. Surgery to remove prostate cancer can affect nerves that supply the bladder and penis, which can affect urinary and sexual function.
The upper part of the prostate is called the base. It rests against the lower part (neck) of the bladder. The lower, narrowed part of the prostate is called the apex. The prostate is divided into a right and a left lobe.
The prostate is made up of many branching ducts surrounded by the stroma. The stroma is made up of connective tissue and muscle fibres. The cells that line the ducts make prostatic fluid, which is mixed with sperm and other fluid to make semen. Most of the prostate is covered by a thin layer of connective tissue called the capsule. The apex of the prostate is covered by the anterior fibromuscular stroma, which is made up of muscle fibres and connective tissue.
The seminal vesicles are glands found on each side of the prostate. They make most of the fluid in semen. The seminal vesicles are sometimes removed during surgery to remove the prostate (called a radical prostatectomy).
The prostate is divided into the following areas.
The peripheral zone is the largest area of the prostate. It can easily be felt by the doctor during a digital rectal exam (DRE). Most prostate cancers start in the peripheral zone.
The transition zone surrounds the part of the urethra that passes through the prostate (called the prostatic urethra). This zone gets bigger as men age, a condition called benign prostatic hyperplasia (BPH).
The central zone lies behind the transition zone and surrounds the ejaculatory ducts, which run from the seminal vesicles to the prostatic urethra. Very few prostate cancers start in the central zone.
The anterior fibromuscular stroma is a thickened area of tissue that surrounds the apex of the prostate. It is made of muscle fibres and fibrous connective tissue. This area of the prostate doesn’t contain any glands. Prostate cancer is rarely found in this part of the prostate.
The main function of the prostate is to make prostatic fluid. Prostatic fluid is rich in enzymes, proteins and minerals that help protect and nourish sperm. When a man is sexually aroused, the prostate pushes prostatic fluid through the ducts and into the urethra. Prostatic fluid mixes with sperm and other fluids in the urethra and is ejaculated as semen.
Hormones, including testosterone and those made by the pituitary gland and adrenal glands, help control the function of the prostate gland.
A physical examination used to check for abnormalities of the rectum or prostate.
During DRE, the doctor inserts a lubricated, gloved finger into the rectum to feel for unusual lumps or enlargement of the prostate.