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To understand prostate
cancer, you must first understand the prostate gland
anatomy and function. Found only in males, the organ
is about the size of a walnut and comprises glandular
tissue and non-glandular tissue. The prostate gland
is an essential part of the male reproductive system.
Without it, most sperm would not survive long after
ejaculation
and die long before reaching an egg.
Where is the Prostate Gland?
The prostate gland sits directly below the bladder and in front of the rectum. Specifically, the prostate is two inches above the perineum, which are the muscles and exterior skin between the scrotum and anus. The seminal vesicles are located near the base. The base refers to the wider part of the anatomy which is located closer to the bladder. The apex is the more narrow part nearer the perineum.
What does the Prostate Gland do?
The function of the prostate gland is to secrete proteins and hormones that are added to the ejaculatory fluid produced by the seminal vesicles. The proteins and hormones aid sperm cells by providing a protective and fluid medium as they make their way through the vagina for fertilization. Without the protective medium, very few sperm cells would ever reach the egg.
Right before ejaculation, sperm enter the vas deferens which is a tube creates a connection to the urethra. The urethra is a tube from the bladder to the tip of penis and creates the exit for semen and urine. Once sperm leave the testicles, they travel to the seminal vesicles which add the bulk of the ejaculatory fluid. At this point, the prostate gland adds the chemicals that help keep sperm alive. The prostate gland and the surrounding muscles contract and expel the semen out of the body through the urethra.
The Prostate Gland Anatomy: Capsule and Zones
The prostate gland anatomy is divided into glandular tissue or non-glandular tissue. As the name would suggest, glandular tissue comprises ducts and glands that secrete fluid. Non-glandular tissue of the prostate is fibromuscular tissue. The prostate gland is classified according to the prostatic capsule and four zones: the anterior, the transition, the central, and the peripheral.
Prostatic Capsule
The prostate gland is encased in a fibromuscular layer and is referred to as the prostatic capsule. Not a true capsule, this layer is most prominent along the base of the prostate gland. Extracapsular extension refers to prostate cancer that has spread outside of the prostate capsule and into the surrounding tissues and organs.
Anterior Zone of the Prostate Gland
Anterior meaning ‘front,’ the anterior zone is located in the front of the prostate gland. Here, the front refers to the part of the prostate gland which is closest to the abdomen rather than the rectum. The anterior zone comprises non-glandular tissue because this zone is composed mostly of muscular tissue.
Transition Zone of the Prostate Gland
The transition zone is the innermost part of the prostate gland and surrounds the urethra where it passes through the organ. The transition zone, along with the central zone, begins to enlarge as men pass age 40. Because of the immediate proximity, to the urethra, the enlargement of this part of the gland can cause difficulty in urination or ejaculation. The transition zone makes up about 5% of the glandular volume and is the site of about 10% of prostate cancers.
The Central Zone of the Prostate Gland
The central zone also begins to enlarge after men pass the age of 40. The central zone surrounds the transition zone and constitutes about 25% of the non-glandular volume. About 5% of prostate cancer cases originate in the central zone.
The Peripheral Zone of the Prostate Gland
The peripheral zone of the prostate gland is located in the back of the prostate gland closest to the rectum. The peripheral zone constitutes about 80% of the prostatic volume and is the site of about 80% of prostate cancer.
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