The prostate gland is major component of male reproductive system. It is an accessory gland that is about the size of a walnut and plays a crucial role in fertilization as its secretions assist with sperm motility and function. The prostate is made up largely of glandular tissue and smaller quantities of fibromuscular tissue.
What does the prostate gland do?
The prostate gland produces a slightly alkaline fluid which adds to the bulk of the ejaculated sperm. The prostatic fluid is a thin, milky fluid containing calcium, citrate, phosphate and enzymes. By neutralizing the acidic environment in the female reproductive tract, prostatic fluid allows sperm to become more motile and fertilize an ovum, if present. Without this contribution, sperm would not function optimally.
Prostate Gland Anatomy
The prostate gland is about the size of a pea at birth and reaches full development around the age of 25 years. At this point, it weighs about 20 grams, measuring about 3 centimeters long, 4 centimeters wide and 2 centimeters deep (front-to-back or AP length).
The prostate gland has a fibrous outer layer that contains several nerves and blood vessels. It is covered by the pelvic fascia which is known as the prostatic sheath. This makes up the prostatic capsule.
The prostate gland has right and left lobes that are separated by a median isthmus of the prostate, also known as the anterior lobe. The right and left lobes can be subdivided into smaller lobules – inferoposterior (lower posterior) lobule, inferolateral (lower outer side) lobule, superomedial (upper inner side) lobule and anteromedial (front inner side) lobule.
Diagram from Wikimedia Commons
However, the prostate gland is often simply divided into just five large lobes, which roughly correspond with the parenchyma tissue. This includes the anterior and posterior lobes, two lateral and a middle (median) lobe. The prostate tissue (parenchyma) can be divided into different zones, namely the peripheral, central and transitions zones, as well as the anterior fibromuscular zone.
There are about 20 to 30 prostatic ducts that open into the prostatitc sinuses found on the posterior wall of the urethra. It empties the prostatic fluid secreted by the prostate gland into the urethra for emission during ejaculation. The prostatic ducts should not be confused with the ejaculatory ducts which stems from the union of the seminal gland ducts and ductus defferentes. The ejaculatory ducts then enter the prostate gland through the posterior wall and empty into the urethra.
Blood Supply to the Prostate Gland
- Prostatic arteries which branch from the internal pudendal, middle rectal and inferior vesical arteries.
- Prostatic venous plexus which empties into the internal iliac veins
Prostate Gland Location
The prostate gland lies in the pelvic cavity, just below the urinary bladder.
Diagram from Wikimedia Commons
The different sides of the prostate gland lie next to or are in contact with the following structures/organs :
- Base of the prostate lie adjacent to the neck of the urinary bladder (above)
- Anterior surface of the prostate is separated from the pubic symphysis by retroperitoneal fat (in front)
- Posterior surface of the prostate in front of the rectum (at the back)
- Inferolateral surface of the prostate related to the levator ani muscles (bottom outer sides)