Reproductive Glands

In previous sections we’ve discussed how sperm are formed in the testicles and pass through the epididymis to help the sperm mature so they can fertile an egg.  Sperm then travel up the vas deferens. The vas deferens is a long tube that rises from the scrotum and into the body, wrapping around the front of the bladder and ending behind the bladder.  At the end of the vas deferens are two large swellings called the ampulla of the vas deferens. 

The ampulla of the vas deferens acts as a reservoir to hold sperm until ejaculation occurs.  Four additional glands in the male reproductive system create fluids to protect and assist sperm in the journey.  Next to the two ampulla are the two seminal vesicles glands.  The ampulla and seminal vesicles empty through the ejaculatory duct into the part of the urethra within prostate gland.  The prostate gland produces prostatic fluid.  When the fluids from the ampulla, seminal vesicles, and prostate combine, they form semen. The urethra passes from the prostate through the pelvic floor muscles and into the penis. 

At the base of the penis, two glands called the bulborethral glands empty into the urethra.  Lining the urethra inside the penis are multiple small glands called the periurethral glands.  The fluids produced by the bulbourethral and periurethral glands form a clear, slippery fluid called pre-ejaculate fluid that flushes out the urethra in preparation for sperm rich semen to pass safely through and out of the urethra of the penis.

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AMPULLA

The two ampulla (one on the right and one on the left) are swelling structures at the end of the vas deferens (one from the right epididymis/testicle, the other from the left).  They are located behind the bladder and their main role is to store sperm until it is ready to be ejaculated. 

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SEMINAL VEISCLES

Lying next to the each ampulla is a seminal vesicle.  The two seminal vesicles look like two narrow sacks and are located behind the bladder.  They are about 2-3 inches in length (5-7cm).  They produce a whole host of nutrients, proteins, and fluids that will make up over half of the semen volume.  Fructose is produced by the seminal vesicles to aid in nutrition for the sperm on their journey to fertilize an egg.  Alkaline or basic compounds (opposite of acidic) are produced here as well – these help neutralize acids, thus allowing sperm to survive in the acidic vaginal environment and givens semen it’s characteristic bleach-like smell.  They also produce a protein that helps sperm to capacitate.  Capacitation is the process that enables sperm to swim.   Other compounds are also released in seminal vesicle fluids including zinc.  Overall, seminal vesicle fluid gives semen its whitish color.

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PROSTATE

The prostate is a small gland, about the size of a walnut that sits at the base of the bladder.  It weighs about an ounce (25-30g).  It actually looks a little bit like an upside down, flattened cone.  The wider portion called the base actually points upwards while the tapered portion that points downwards is called the apex.  The urethra exits the bladder and enters the base of the prostate where it passes through the prostate and exits at the apex before continuing then on out through the penis. 

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One of the roles of the prostate is to create prostatic fluid.  Prostatic fluid is a thick, semi-clear to light yellow fluid, not white.  It is released (squeezed) through the prostatic ducts in the urethra of the prostate.  Prostate fluid contains enzymes that help thin out semen after ejaculation, thus making it easier for sperm to swim.  Prostate fluid can sometimes be seen after a man has a bowel movement (the stool may press the prostate through the rectum enough to press prostate fluid through the prostatitc ducts and into the urethra).  Some men mistake this as a few drops of urine but it is thick and sticky rather than thin and watery like urine. 

Because the prostate gland is so complex and can create a whole host of symptoms and disorders in men, we will discuss the anatomy of the prostate in more detail in the prostate section.

 

BULBOURETHRAL GLANDS

"COWPER'S GLANDS"

The two bulbourethral glands sit on either side of the urethra at the base of the penis.  Each gland is the about the size of a pea, with a duct that opens directly to the urethra in the base of the penis.  These glands produce the majority of pre-ejaculate fluid. Image below copyrighted by DNA Illustrations and used by permission.

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PERIURETHRAL GLANDS

"GLANDS OF LITTRE"

Tiny glands called the periurethral glands or glands of Littre line much of the rest of the urethra within the penis. The glands of Littre produce a very small amount of mucus to lubricate the urethra in preparation for ejaculation.  These glands contribute small amounts of secretions to pre-ejaculate fluid. 

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FUNCTIONS OF THE REPRODUCTIVE GLANDS

The role of the male sexual glands is to produce various fluids that prepare the pathway for sperm to pass out of the male body.  This occurs by creating pre-ejaculate fluid to cleanse and neutralize acids found in urine, and semen to nourish and provide fluid for the sperm to swim in.  

Disorders affecting the male reproductive glands and sexual fluids

Disorders of the sexual glands are perhaps the most common disorders faced by men.  

Images on this page from top to bottom include:

  1. Sergeant Illustration, Owned

  2. Sergeant Illustration, Owned

  3. SciePro/Shutterstock.com

  4. CLIPAREA/Shutterstock.com

  5. DNA Illustrations and used by permission.

  6. Sergeant Illustration, Owned