Biology

Male accessory sex organs

len Alfred Ajibola - Tue, 06th August, 2019 @ 15:29: PM

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Male Accessory Sex organs:

The male accessory sex glands are very important in the formation of semen. Without their secretions, the released sperm (via ejaculation) may not be able to fertilize the female's ova (egg).

In a previous article, we looked at the penis, scrotum, testes, epididymis, spermatic cord, cremaster muscles and vas deferens (as structures of the male reproductive system).

Please read on the Male Reproductive System here.

The male accessory sex glands include:

  1. Seminar vesicles
  2. Prostate gland
  3. Bulbourethral glands or Cowper’s gland

The glands (above) are called accessory because they interact with the male sex cells (sperm) on their path on being released from the external urethral orifice in the penis. (Think of the external urethral orifice as the opening on the tip of the penis).

Note: The accessory glands are also vital in the normal functioning of sperm cells. Their secretions together with the sperm give rise to semen.

In order to better comprehend the male accessory glands, let's make some quick points on the ejaculatory ducts.

 

  • Ejaculatory Ducts

Also called the ductus ejaculatorii, they are paired structures formed by the union of the vas deferens or ductus deferens and the duct of the seminal vesicle.

The ejaculatory ducts, which are about 2cm in length functions to convey semen as it travels into the prostate gland and eventually drains into the urethra.

Notice the ejaculatory ducts in the diagram; (as explained in the above paragraph):

Male Accessory Sex Organs - Len Academy
Image Credit: DocPlayer

Note the Followings:

Blockage of the ejaculatory ducts will result in a clinical condition called Ejaculatory Duct Obstruction.

If both ducts are obstructed, the patient will suffer from either aspermia (an absence of sperm) or azoospermia (low sperm count).

The operation carried out to remove the obstructed or blocked ejaculatory ducts is termed Transurethral Resection.

 

Now, let's look into the male accessory glands of reproduction.

  • Prostate Gland

Located between the bladder and the penis (and just in front of the rectum) is the prostate gland which is a muscular structure that looks like the size of a walnut. (See the diagram below:)

Prostrate Gland - Len Academy
Image Credit: DocPlayer

Note: The above diagram will be referenced in the explanations on Seminal Vesicles and Bulbourethral Glands; which are the other accessory male organs of reproduction.

It is the function of the prostate gland to secrete fluid (called prostatic fluid) into the contents of the ejaculatory duct (that is; sperm).

The prostatic fluid (somewhat milky in appearance) is vital for the normal functioning of sperm; in addition to protecting it.

Note: Also attached to the prostate are the seminal vesicles which secrete some additional fluid (called seminal fluid) into the sperm before ejaculation occurs.

The prostatic fluid (slightly acidic) and seminal fluid (alkaline), together with other fluids secreted into the sperm give rise to semen.

Overall, the semen is slightly alkaline; and this helps to counteract the acidity of the vagina, thus protecting the sperm inside the vagina.

For ejaculation to occur in males, the prostate gland must contract, thus pushing the semen into the urethra.

During this process of contraction, the opening between the bladder and urethra is obstructed (closed); and for this reason, a male cannot urinate and ejaculate simultaneously (at the same time). Please see the above diagram.

Note: Urine flows from the bladder into the urethra.

As a male advances in age, they become more likely to have some clinical issues with their prostate gland.

Below are two clinical prostate conditions:

1. Prostate Cancer: This is one of the commonest cancers in males. When a patient delays the surgical operation of a prostate cancer, it’s called watchful waiting. It can be treated surgically via the removal of the prostate organ, or by radiation or hormonal therapy.

2. Prostatitis: This is an inflammation of the prostate gland. It is usually treated by using the appropriate antibiotics, as prescribed by the doctor.

Please read on the Type of Drugs and their Side Effects here.

 

  • Seminal Vesicles

A male has a pair of seminal vesicles located posterior to the base of the urinary bladder and just in front of the rectum. (Please see the image for Prostate Gland above).

The function of the seminal vesicles is to add some viscous and alkaline secretions to the sperm already present in the ejaculatory ducts.

The alkalinity of this fluid helps to neutralize any acidity produced in the environment of the urethra; (which may result from the passage of acidic urine through it).

Similarly, they also neutralize the acidic environment of the vagina hence fostering sperm survival within it.

The Seminal Fluid is made up of the followings:

  1. Fructose: This is a simple sugar that's used for ATP (Adenosine Tri Phosphate) generation.
    ATP is the energy essential for sperm motility (as it swims upward in the female reproductive tract).

    For now, think of ATP as the energy currency of the body.
    Please read on Carbohydrates and Sugars here.

  2. Prostaglandins: They reduce the negative effects of the female immune system acting on the sperm; thus increasing the survival chance of the sperms.
    Please read on Immunization here.

  3. Semenogelin: This fluid creates a gel like structure around the sperm, thus protecting it.
    Also, the appearance of semen is largely due to semenogelin.

 

  • Bulbourethral Glands

They are also called the Cowper’s gland.

The bulbourethral glands are two pea like shaped organs located just below the prostate gland at the beginning of the root of the penis. (Please see the diagram above).

In addition to the prostate and seminal fluids, the Bulbourethral glands also secrete fluid into the semen during the process of ejaculation.

The fluids of the bulbourethral glands are clear and thick, functioning to lubricate the urethra. (The semen follows through the lubricated urethra).

It is also considered that the bulbourethral secretions creates a better condition for sperm cells to survive.

 

Note: Although the urethra is not a part of the male accessory reproductive glands, it still has a part to play in the male reproductive system.

Below is a summary on the urethra:

  • Urethra

The male urethra is a single structure that serves two functions. These are:

Micturition. (The act of urinating).

Conduction and Movement of semen during ejaculation.

In males, the urethra is a narrow fibro-muscular tube that conducts urine from the bladder to the exterior. It also conducts semen from the ejaculatory ducts to the exterior.

The conduction on urine and semen through the urethra does not occur simultaneously. (Please see the urethra in the previous diagram).

Note: The male urethra is about 7 to 8 inches in length; and it runs through the prostate gland, seminal vesicles and the entire length of the penis before emptying its content to the exterior.

The urethra has three sections. These are:

1. Prostatic urethra: This is the uppermost portion of the urethra. It lies inside the prostate gland.

2. Membranous urethra: This is the segment within the urethral sphincter.

Urine or Semen can only come out one at a time; (when the membranous urethra is opened).

3. Spongy urethra: This is the lowest and longest section of the urethra. It lies within the entire length of the penis to the exterior.

Note: The exterior opening of the urethra is also called the external urethral orifice or meatus).


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len

Alfred Ajibola is a Medical Biochemist, a passionate Academician with over 7 years of experience, a Versatile Writer, a Web Developer, a Cisco Certified Network Associate and a Cisco CyberOps Associate.


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